Porous catalytic matrices for elimination of toxicants found in tobacco combustion products

ABSTRACT

Described herein are compositions and methods for capturing carbonylic or phenolic toxicants, or converting these toxicants into less volatile compounds. The toxicants, which may be a component of cigarette smoke, may be captured by physical or chemical adsorption, absorption, or entrapment.

RELATED APPLICATIONS

This application is the U.S. National Stage of International ApplicationNo. PCT/US12/049170, filed Aug. 1, 2012, which is a continuation-in-partapplication of U.S. patent application Ser. No. 13/195,378, filed Aug.1, 2011.

BACKGROUND

Cigarette smoking is believed to contribute to or cause roughly 30% ofall cancer deaths. Cigarette smoke contains more than 3500 chemicals, atleast 50 of which are carcinogens. Carbonyls, including acetaldehyde,acrolein (propenal), formaldehyde, and others, are formed through thepyrolysis of tobacco. Accordingly, these compounds are among thecompounds present at high levels in cigarette smoke. In fact,acetaldehyde and acrolein are present in international brands ofcigarettes at concentrations of 860 and 83 μg/mg of nicotine,respectively. The Scientific Basis of Tobacco Product Regulation, WHOTechnical Report Series 951, World Health Organization, Geneva,Switzerland, 2008. Long-term exposure to formaldehyde, acrolein, andacetaldehyde is known to increase the risk of asthma and cancer.

Cigarette smoke and tar also contain other carcinogens, such aspolycyclic aromatic alcohols, which initiate the formation of cancer.Co-carcinogens in cigarette smoke, such as phenols, have also beenidentified; co-carcinogens accelerate the production of cancer by otherinitiators. Many phenols, naphthols and other co-carcinogens are alsoirritants.

The World Health Organization (WHO) has recommended mandated lowering ofallowable levels of these toxicants in cigarettes. Current methods ofreducing the amount of a toxicant in cigarette smoke includeincorporation of transition metal oxide clusters, such as clusters ofscandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel,copper, and oxides and mixtures thereof. The nano-sized clusters ornanoparticles of metal oxide are capable of catalyzing the conversion(oxidation) of carbon monoxide (CO) to carbon dioxide (CO₂), oradsorbing carbon monoxide itself. The clusters are incorporated into acomponent of a smoking article, wherein the component is selected fromthe group consisting of tobacco cut filler, cigarette paper andcigarette filter material. See U.S. Pat. No. 7,712,471, incorporatedherein by reference in its entirety. However, this reference notdisclose any methods for reducing the levels of toxicants other than COin the cigarette smoke.

Another method of reducing toxicants in cigarette smoke is disclosed inU.S. Pat. No. 6,615,843, hereby incorporated by reference in itsentirety. This patent discloses a tobacco smoke filter synergisticcomposition comprised of antioxidants, such as ascorbic or citric acid,butylparaben, glutathione, melatonin, resveratrol, selenium,ubiquinones, or green tea, and adsorptive “minerals,” such as activatedcarbon, clinoptilolite, cuprous chloride, and ferrite. The antioxidantsare effective as scavengers in reducing free radicals from the cigarettesmoke, while activated carbon or similar adsorbent ‘minerals’ adsorbsubstantial levels of volatiles. However, U.S. Pat. No. 6,615,843 doesnot disclose any catalytic conversion of the volatile carbonyliccompounds or phenols into less volatile chemicals. No catalyticcondensation reactions of phenols and aldehydes found as toxicants inthe cigarette smoke were disclosed.

Separately, metal-organic frameworks (MOF), constituted by metal ions ormetal ion clusters occupying nodal framework positions coordinated withdi- or multi-podal organic ligands, are rapidly emerging as an importantfamily of crystalline materials to be utilized as catalysts in organicreactions. Some of these MOFs are crystalline materials with the lowestframework densities and the highest pore volume known to date. Amongover 10,000 MOF materials, there are several transition-metal MOFs thatare stable under liquid-phase reaction conditions. These includemesoporous chromium (III) terephthalate (MIL-101), which possessesacceptable resistance to water, common solvents, and temperatures (up to320° C.). MIL-101 has a rigid zeotype crystal structure, consisting of2.9 and 3.4-nm quasi-spherical cages accessible through windows of ca.1.2 and 1.6 nm, respectively. Due to the high stability, MIL-101exhibits no detectable leaching of chromium into solutions, allowing itssafe use in different applications. In addition, MIL-101 possess a highdensity of chromium ions (three per elementary cell) with Lewis acidproperties, which can be stable under reaction conditions. The open-porestructure of MIL-101 can be further functionalized by Pd or Aunanoparticles and polyoxometalate (POM) anions. The resulting compositematerials are effective catalysts for hydrogenation reactions andoxidation reactions. Another POM material that can be utilized tofunctionalize the MIL-101 framework is phosphotungstic acid (PTA). PTAis the strongest known heteropolyacid. MIL-101/PTA composite materials(MIL101/PTA) have been shown to catalyze (i) the oxidation on of alkenesusing molecular oxygen and aqueous hydrogen peroxide as oxidants, (ii)H₂O₂-based alkene epoxidations, (iii) the Knoevenagel condensation ofbenzaldehyde and ethyl cyanoacetate, (iv) liquid and gas-phaseacid-catalyzed esterifications (acetic acid with n-butanol, methanoldehydration), and (v) and carbohydrate dehydration.

SUMMARY OF THE INVENTION

In certain embodiments, the invention relates to a method of reducingthe quantity of a toxicant in a fluid, comprising

contacting the fluid with a MOF matrix,

wherein

the MOF matrix comprises metal ions or clusters coordinated topolydentate organic ligands;

the fluid is a gas; and

the toxicant is a carbonylic compound or a phenolic compound.

In certain embodiments, the invention relates to any one of theaforementioned methods, wherein the fluid is tobacco smoke.

In certain embodiments, the invention relates to a method of adsorbingor absorbing a carbonylic compound or a phenolic compound, comprising

contacting the carbonylic compound or phenolic compound with a MOFmatrix, wherein the MOF matrix comprises metal ions or clusterscoordinated to polydentate organic ligands.

In certain embodiments, the invention relates to a method of catalyzingthe conversion of a carbonylic compound to a non-carbonylic product,comprising

contacting the carbonylic compound with a MOF matrix for an amount oftime, thereby forming the non-carbonylic product, wherein the MOF matrixcomprises metal ions or clusters coordinated to polydentate organicligands.

In certain embodiments, the invention relates to a method of catalyzingthe conversion of a phenolic compound to a non-phenolic product or apolymeric product, comprising

contacting the phenolic compound with a MOF matrix for an amount oftime, thereby forming the non-phenolic product or the polymeric product,wherein the MOF matrix comprises metal ions or clusters coordinated topolydentate organic ligands.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 depicts typical BET nitrogen adsorption isotherms for MIL-101 andMIL101/PTA hybrid material at 77 K. P/P₀ is the ratio of gas pressure(P) to saturation pressure (P₀), with P₀=746 torr.

FIG. 2 depicts equilibrium acrolein uptake by exemplary porous matricesand exemplary compounds of the present invention at room temperature.

FIG. 3 depicts a schematic of acrolein polymerization in the presence ofthe strong bases or acids of exemplary matrices of the presentinvention.

FIG. 4 depicts equilibrium acetaldehyde uptake by exemplary porousmatrices of the present invention and phosphotungstic acid (PTA) at roomtemperature.

FIG. 5 depicts typical MALDI-TOF spectrum of the liquid condensed overMIL101/PTA_(ja) matrix after 2 days of exposure to acetaldehyde vaporsat room temperature (peaks have no indicator). Also shown is a spectrumof α-cyano-4-hydroxycinnamic acid (ACHCA) matrix (indicated by *). Forthe measurement, 1 μL of the liquid was lyophilized, reconstituted in 1μL of ACHCA matrix solution, spotted and analyzed.

FIG. 6 depicts a schematic showing a reaction between benzaldehyde and2-naphthol catalyzed by a porous matrix of the present invention.

FIG. 7 tabulates properties of MIL-101 (Cr) particles synthesized indeionized water at pH 2.6. ^(a) Yield is calculated using chromiumcontent in purified particles vs initial chromium content set in thesynthesis. ^(b) Measured in particle suspension in methanol. ^(c)Determined from nitrogen adsorption isotherms. ^(d) Computed usinginstrument's built-in software using Barrett, Joyner & Halenda method.

FIG. 8 tabulates properties of MIL101/PTA hybrid materials synthesizedby joint autoclaving of the MIL-101 components and PTA in deionizedwater (MIL101/PTAja) or by impregnation of MIL-101 by PTA in water.^(a)Determined from nitrogen adsorption isotherms. ^(b)Obtained fromelemental analysis and calculations based on Keggin structure(H₃PW₁₂O₄₀)

FIG. 9 tabulates Baeyer condensations of aldehyde and β-naphtholcatalyzed by MOF MIL-101 and its polyoxometalate composites and PTA.^(a)In all cases, except for catalysis with phosphotungstic acid (PTA),the catalyst loading is given in wt %. The loading is calculated as 100×catalyst weight/sum of weight of all components in the initial reactionmixture. ^(b)PTA loading is given in wt %/mol %. The content in mol % iscalculated as 100× mols of catalyst/sum of mols of each component in theinitial reaction mixture. ^(c)MW is the time of microwaving, whereinspecified temperature is held within the reaction tube. ^(d)Series ofindependent experiments conducted in triplicate demonstrated standarddeviations of the yield determination to be within ±5 wt %. ^(e)MIL-101samples prepared using autoclaving method are used throughout.

FIG. 10 tabulates properties of MIL-101 metal organic framework andMIL101/PTA composite materials synthesized by impregnation of MIL-101 byPTA in water (MIL101/PTA_(imp)) or by joint autoclaving of the MIL-101components and PTA in deionized water (MIL101/PTA_(ja)). ^(a)Obtainedfrom elemental analysis and calculations based on Keggin structure(H₃PW₁₂O₄₀). ^(b)Measured by dynamic light scattering in particlesuspension in methanol. ^(c)Determined from nitrogen adsorptionisotherms.

FIG. 11 depicts a scheme showing acid-catalyzed aldol condensation ofacetaldehyde.

FIG. 12 depicts typical ¹H NMR spectra representing the kinetics of theacetaldehyde and phenol condensation reaction catalyzed byMIL-101/PTA_(ja) in THF-d₈ at 25° C.C_(a0)/C_(p0)=2:1 (mol/mol). Numbersstand for time in minutes since the reaction commencement. Letters A andP indicate the aldehyde (substrate) and product signals, respectively.

FIG. 13 depicts the Baeyer condensation of acetaldehyde and phenol.

FIG. 14 depicts acetaldehyde conversion (F) vs time in theacetaldehyde-phenol (A-P) condensation reaction in deuterated THF.Initial acetaldehyde and phenol concentrations were C_(a0)=C_(pi)=0.33M. T=25° C. For F definition, see equation (1).

FIG. 15 depicts a plot of the initial kinetics of acetaldehydeconversion in the Baeyer acetaldehyde-phenol condensation expressed interms of

$P = {\frac{\ln\; C_{a}}{q + C_{a\; 0}} - \frac{\ln\; C_{a}}{q + C_{a}}}$vs time (equation (2)).

FIG. 16 tabulates effective catalyst concentration (C_(cat)), reactionhalf-life (t_(1/2)), kinetic rate constant, and turnover frequency (TOF)of the acetaldehyde-phenol condensation conducted in THF-d₈ at 25° C.and C_(a0)=C_(pi)=0.33 M. ^(a)Concentration of PTA in solution.^(b)Concentration of PTA in the MIL101/PTA calculated per L of thesuspension. ^(c)Total concentration of the Brønsted and Lewis acid citesper L of the suspension. ^(d)Calculated from the expressionTON=C_(a0)×F/C_(cat). Here, F (equation (1)) is measured at 10 h afterthe reaction commencement.

FIG. 17 depicts a schematic showing the reaction between benzaldehydeand methanol.

FIG. 18 depicts typical ¹H NMR spectra illustrating the kinetics of thereaction of benzaldehyde acetalization by methanol catalyzed byMIL101/PTA_(ja) at 25° C. Initial concentrations of methanol andbenzaldehyde are C_(mi)=23.5 and C_(b0)=0.474 M, respectively. Samplesof the reaction mixture withdrawn at timepoints indicated were dissolvedin CDCl₃ at 2:5 vol/vol ratio after catalyst separation. Numbers standfor time in minutes since the reaction commencement. Letters A and Pindicate the aldehyde (substrate) and product signals, respectively.

FIG. 19 depicts a kinetic plot of benzaldehyde conversion in itsacetalization by methanol catalyzed by MIL-101, MIL101/PTA_(ja),MIL101/PTA_(imp) and PTA at 25° C. The straight lines illustrate theinitial reaction rates and are shown to guide the eye only.

FIG. 20 tabulates the effective catalyst concentration (C_(cat)),observed rate constant (k_(obs)), reaction half-life (t_(1/2)), andturnover frequency (TOF) of the acetalization of benzaldehyde withmethanol conducted at 25° C. and C_(b0)=0.474 M,C_(mi)=23.5 M.^(a)Concentration of PTA in solution. ^(b)Concentration of PTA in theMIL101/PTA calculated per L of the suspension. ^(c)Total concentrationof the Brønsted and Lewis acid cites per L of the suspension.^(d)Calculated from the expression t_(1/2)=ln(2)/k_(obs). ^(e)Calculatedfrom the expression TON=C_(b0)×F/C_(cat). Here, F (eqn (4)) is measuredat 24 h after the reaction commencement.

FIG. 21 tabulates total catalyst recovery, Keggin ion content, Crcontent and kinetic rate constants measured in 4 cycles of catalystreuse. Each cycle consisted of 1 day of the catalytic reaction at 25°C., catalyst recovery, workup and reuse as described. ^(a)Calculated as100× mass of catalyst in n-th cycle/initial mass of catalyst.^(b)Measured by elemental analysis in each cycle. ^(c)Rate constants kand k_(obs) are measured in the acetaldehyde-phenol andbenzaldehyde-methanol reactions, respectively.

FIG. 22 depicts structures of NH₂-MIL-101(Al) (left) showing larger andsmaller spherical pores and NH₂-MIL-53(Al) (right). The inorganiccluster is represented by grey-colored octahedron, the amino group isrepresented by a sphere.

FIG. 23 depicts acetaldehyde vapor uptake at 25° C. and BET area ofMOFs. See the text for MOF designations.

FIG. 24 depicts the aldol condensation of acetaldehyde catalyzed by PTA.

FIG. 25 depicts MALDI-TOF spectrum of the sorbate extract fromNH₂MIL101(Al)/PTA_(imp) sample equilibrated with acetaldehyde vapor at25° C. Asterisk shows peaks belonging to the DHB matrix, whereas numbersstand for identified compounds of acetaldehyde conversion. Theidentified compounds are shown in the insets.

FIG. 26 depicts MALDI-TOF spectrum of the aqueous solution ofNH₂MIL101(Al)/PTA_(imp) reacted with acetaldehyde vapor at 25° C. for 24h. Asterisks shows peaks of the DHB matrix, whereas numbers stand foridentified compounds.

FIG. 27 depicts the mechanism of the acetaldehyde-amine/MOF condensationleading to the formation of imine groups.

FIG. 28 depicts SEM images illustrating coating of the cellulose acetatefibers (PMI) with MOF particles. Uncoated fibers are shown in the leftupper image.

FIG. 29 depicts a schematic of the reaction between 2-aminoterephthalicacid of MOF and TDI.

FIG. 30 depicts acetaldehyde vapor uptake and BET surface area ofcellulose acetate (CA) fibers, CA film cast from acetone, and CA fibersmodified by MOF materials. The vapor uptake was measured for 24 h at 25°C.

DETAILED DESCRIPTION

Overview

In certain embodiments, the present invention relates to materials andmethods for filtering tobacco smoke. In certain embodiments, the presentinvention relates to materials and methods for filtering cigarettesmoke. In certain embodiments, the materials are capable of capturingtoxicant vapors and particles, and tar and other health-damagingmaterials, arising from the combustion of tobacco.

In certain embodiments, the invention relates to a method of capturingand converting carbonylic compounds into less volatile compounds. Incertain embodiments, the capturing occurs via physical or chemicaladsorption, absorption, or entrapping toxicant components of thecigarette smoke and smoke constituents.

In certain embodiments, the invention relates to a filter to be used bya person smoking tobacco, wherein the filter is capable of reducing theamount of contaminants in smoke passing through the filter (i.e., intothe person's mouth).

In certain embodiments, the invention relates to a method of filteringtobacco smoke. In certain embodiments, the method combines absorptionand catalytic reduction of the noxious components of the smoke.

Exemplary Matrices of the Invention

Overview

In certain embodiments, the invention relates to a metal-organicframework (MOF) matrix. In certain embodiments, the invention relates toany one of the aforementioned MOF matrices, wherein the MOF matrixcomprises metal ions or clusters coordinated to organic ligands. Incertain embodiments, the invention relates to any one of theaforementioned MOF matrices, wherein the MOF matrix comprises metal ionsor clusters coordinated to polydentate organic ligands.

In certain embodiments, the invention relates to any one of theaforementioned MOF matrices, wherein the MOF matrix comprises at leastone, at least bidentate, organic ligand bound by coordination to atleast one metal ion. In certain embodiments, the invention relates toany of the MOF matrices described in U.S. Pat. No. 5,648,508 or U.S.Pat. No. 7,842,827, both of which are hereby incorporated by referencein their entireties.

In certain embodiments, the invention relates to any one of theaforementioned MOF matrices, wherein the MOF matrix comprises MIL-101 orMIL101/PTA. MIL-101 is a chromium terephthalate-based mesoscopicmetal-organic framework and one of the most porous materials reported todate.

In certain embodiments, the invention relates to any one of theaforementioned MOF matrices, wherein the MOF matrix comprises MIL-101,strongly acidic MIL-101, or MIL101/PTA. In certain embodiments, theinvention relates to any one of the aforementioned MOF matrices, whereinthe MOF matrix is MIL-101, strongly acidic MIL-101, or MIL101/PTA.

In certain embodiments, the invention relates to any one of theaforementioned MOF matrices, wherein the MOF matrix is selected from thegroup consisting of MOF-177, MOF-178, MOF-74, MOF-235, MOF-236, MOF-69to 80, MOF-501, MOF-502, and MOF-101. In certain embodiments, theinvention relates to any one of the aforementioned MOF matrices, whereinthe MOF matrix is selected from the group consisting of MOF-2 to 4,MOF-9, MOF-31 to 36, MOF-39, MOF-69 to 80, MOF103 to 106, MOF-122,MOF-125, MOF-150, MOF-177, MOF-178, MOF-235, MOF-236, MOF-500, MOF-501,MOF-502, MOF-505, IRMOF-1, IRMOF-61, IRMOP-13, IRMOP-51, MIL-17, MIL-45,MIL-47, MIL-53, MIL-59, MIL-60, MIL-61, MIL-63, MIL-68, MIL-79, MIL-80,MIL-83, MIL-85, CPL-1 to 2, and SZL-1.

Exemplary Metal Components of Matrices of the Invention

In certain embodiments, the invention relates to any one of theaforementioned MOF matrices, wherein the metal ion or cluster comprisesa metal atom of group Ia, IIa, IIIa, IVa to VIIIa, or Ib to VIb. Incertain embodiments, the invention relates to any one of theaforementioned MOF matrices, wherein the metal ion or cluster comprisesMg, Ca, Sr, Ba, Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ro,Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge,Sn, Pb, or Bi. In certain embodiments, the invention relates to any oneof the aforementioned MOF matrices, wherein the metal ion or clustercomprises Zn, Cu, Ni, Pd, Pt, Ru, Rh, or Co. In certain embodiments, theinvention relates to any one of the aforementioned MOF matrices, whereinthe metal ion or cluster comprises Cr, Fe, Zn, Al, Ni, or Cu.

In certain embodiments, metal ions or clusters are described in U.S.Pat. No. 5,648,508, hereby incorporated by reference in its entirety.

Exemplary Organic Ligands of the Invention

In certain embodiments, the invention relates to any one of theaforementioned MOF matrices, wherein the polydentate organic ligand isan organic ligand that is attached to a central metal ion by bonds fromtwo or more donor atoms. In certain embodiments, the polydentate organicligand is bidentate, tridentate, or tetradentate.

In certain embodiments, the invention relates to any one of theaforementioned MOF matrices, wherein the term “at least bidentateorganic compound” designates an organic compound that comprises at leastone functional group that is able to form, to a given metal ion, atleast two coordinate bonds, or to two or more metal atoms, in each caseone coordinate bond. In certain embodiments, the organic compound isable to form three coordinate bonds to one metal atom. In certainembodiments, the organic compounds is able to form one coordinate bondto each of three metal atoms.

In certain embodiments, the invention relates to any one of theaforementioned MOF matrices, wherein the organic ligand comprises afunctional group selected from the group consisting of —COOH, —NO₂,—B(OH)₂, —SO₃H, —Si(OH)₃, —Ge(OH)₃, —Sn(OH)₃, —Si(SH)₃, —PO₃H,—CH(RNH₂)₂, —C(RNH₂)₃, —CH(ROH)₂, —R(OH)₃, —CH(RCN)₂, —C(RCN)₃,

and R is an alkylene group having 1, 2, 3, 4, or 5 carbon atoms, or anarylene group comprising 1 or 2 aromatic nuclei. In certain embodiments,the invention relates to any one of the aforementioned MOF matrices,wherein R is methylene, ethylene, n-propylene, i-propylene, n-butylene,i-butylene, tert-butylene, or n-pentylene. In certain embodiments, theinvention relates to any one of the aforementioned MOF matrices, whereinR comprises two phenylene rings. In certain embodiments, the inventionrelates to any one of the aforementioned MOF matrices, wherein Rcomprises a heteroarylene group, wherein the heteroatom is N, O, or S.In certain embodiments, the invention relates to any one of theaforementioned MOF matrices, wherein R is substituted by at least ineach case one substituent. In certain embodiments, R is not present. Incertain embodiments, the invention relates to any one of theaforementioned MOF matrices, wherein the organic ligand comprises afunctional group selected from the group consisting of —CH(SH)₂,—C(SH)₃, —CH(NH)₂, —C(NH₂)₃, —CH(OH)₂, —C(OH)₃, —CH(CN)₂ and —C(CN)₃.

In certain embodiments, the invention relates to any one of theaforementioned MOF matrices, wherein the organic ligand is derived froma saturated or unsaturated aliphatic compound, an aromatic compound, ora compound that is both aliphatic and aromatic.

In certain embodiments, the invention relates to any one of theaforementioned MOF matrices, wherein the organic ligand is trans-muconicacid, fumaric acid, or phenylenebisacrylic acids.

In certain embodiments, the invention relates to any one of theaforementioned MOF matrices, wherein the organic ligand is an optionallyat least monosubstituted mono-, di-, tri-, tetranuclear, or highernuclear aromatic, di-, tri- or tetracarboxylic acid. In certainembodiments, the invention relates to any one of the aforementioned MOFmatrices, wherein any of the aromatic nuclei is a heteroaromatic nuclei.In certain embodiments, the invention relates to any one of theaforementioned MOF matrices, wherein the organic ligand is a mononucleardicarboxylic acid, mononuclear tricarboxylic acid, mononucleartetracarboxylic acid, dinuclear dicarboxylic acid, dinucleartricarboxylic acid, dinuclear tetracarboxylic acid, trinucleardicarboxylic acid, trinuclear tricarboxylic acid, trinucleartetracarboxylic acid, tetranuclear dicarboxylic acid, tetranucleartricarboxylic acid, or tetranuclear tetracarboxylic acid. In certainembodiments, the invention relates to any one of the aforementioned MOFmatrices, wherein any of the aromatic nuclei is a heteroaromatic nuclei.In certain embodiments, the invention relates to any one of theaforementioned MOF matrices, wherein any of the aromatic nuclei is aheteroaromatic nuclei; and the heteroatom is N, O, S, B, P, Si, or Al.In certain embodiments, the invention relates to any one of theaforementioned MOF matrices, wherein any of the aromatic nuclei is aheteroaromatic nuclei; and the heteroatom is N, S or O. In certainembodiments, the invention relates to any one of the aforementioned MOFmatrices, wherein the organic ligand is substituted; and the substituentis —OH, —NO₂, amino, alkyl, or alkoxy.

In certain embodiments, the invention relates to any one of theaforementioned MOF matrices, wherein the organic ligand is adicarboxylic acid, including but not limited to asoxalic acid, succinicacid, tartaric acid, 1,4-butanedicarboxylic acid,4-oxopyran-2,6-dicarboxylic acid, 1,6-hexanedicarboxylic acid,decanedicarboxylic acid, 1,8-heptadecanedicarboxylic acid,1,9-heptadecanedicarboxylic acid, heptadecanedicarboxylic acid,acetylenedicarboxylic acid, 1,2-benzenedicarboxylic acid,2,3-pyridinedicarboxylic acid, pyridine-2,3-dicarboxylic acid,1,3-butadiene-1,4-dicarboxylic acid, 1,4-benzenedicarboxylic acid,p-benzenedicarboxylic acid, imidazole-2,4-dicarboxylic acid,2-methylquinoline-3,4-dicarboxylic acid, quinoline-2,4-dicarboxylicacid, quinoxaline-2,3-dicarboxylic acid,6-chloroquinoxaline-2,3-dicarboxylic acid,4,4′-diaminophenylmethane-3,3′-dicarboxylic acid,quinoline-3,4-dicarboxylic acid,7-chloro-4-hydroxyquinoline-2,8-dicarboxylic acid, diimidodicarboxylicacid, pyridine-2,6-dicarboxylic acid, 2-methylimidazole-4,5-dicarboxylicacid, thiophene-3,4-dicarboxylic acid,2-isopropylimidazole-4,5-dicarboxylic acid,tetrahydropyran-4,4-dicarboxylic acid, perylene-3,9-dicarboxylic acid,perylenedicarboxylic acid, Pluriol E 200-dicarboxylic acid,3,6-dioxaoctanedicarboxylic acid, 3,5-cyclohexadiene-1,2-dicarboxylicacid, octadicarboxylic acid, pentane-3,3-carboxylic acid,4,4′-diamino-1,1′-diphenyl-3,3′-dicarboxylic acid,4,4′-diaminodiphenyl-3,3′-dicarboxylic acid, benzidine-3,3′-dicarboxylicacid, 1,4-bis(phenylamino)benzene-2,5-dicarboxylic acid,1,1′-dinaphthyl-S,S′-dicarboxylic acid,7-chloro-8-methylquinoline-2,3-dicarboxylic acid,1-anilinoanthraquinone-2,4′-dicarboxylic acid,polytetrahydrofuran-250-dicarboxylic acid,1,4-bis(carboxymethyl)piperazine-2,3-dicarboxylic acid,7-chloroquinoline-3,8-dicarboxylic acid,1-(4-carboxy)phenyl-3-(4-chloro)phenylpyrazoline-4,5-dicarboxylic acid,1,4,5,6,7,7-hexachloro-5-norbornene-2,3-dicarboxylic acid,phenylindanedicarboxylic acid,1,3-dibenzyl-2-oxoimidazolidine-4,5-dicarboxylic acid,1,4-cyclohexanedicarboxylic acid, naphthalene-1,8-dicarboxylic acid,2-benzoylbenzene-1,3-dicarboxylic acid,1,3-dibenzyl-2-oxoimidazolidine-4,5-cis-dicarboxylic acid,2,2′-biquinoline-4,4′-dicarboxylic acid, pyridine-3,4-dicarboxylic acid,3,6,9-trioxaundecanedicarboxylic acid, O-hydroxybenzophenonedicarboxylicacid, Pluriol E 300-dicarboxylic acid, Pluriol E 400-dicarboxylic acid,Pluriol E 600-dicarboxylic acid, pyrazole-3,4-dicarboxylic acid,2,3-pyrazinedicarboxylic acid, 5,6-dimethyl-2,3-pyrazinedicarboxylicacid, 4,4′-diaminodiphenyletherdiimidodicarboxylic acid,4,4′-diaminodiphenylmethanediimidodicarboxylic acid,4,4′-diaminodiphenylsulfonediimidodicarboxylic acid,2,6-naphthalenedicarboxylic acid, 1,3-adamantanedicarboxylic acid,1,8-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid,8-methoxy-2,3-naphthalenedicarboxylic acid,8-nitro-2,3-naphthalenecarboxylic acid,8-sulfo-2,3-naphthalenedicarboxylic acid, anthracene-2,3-dicarboxylicacid, 2′,3′-diphenyl-p-terphenyl-4,4″-dicarboxylic acid,diphenyl-ether-4,4′-dicarboxylic acid, imidazole-4,5-dicarboxylic acid,4(1H)-oxothiochromene-2,8-dicarboxylic acid,5-tert-butyl-1,3-benzenedicarboxylic acid, 7,8-quinolinedicarboxylicacid, 4,5-imidazoledicarboxylic acid, 4-cyclohexene-1,2-dicarboxylicacid, hexatriacontanedicarboxylic acid, tetradecanedicarboxylic acid,1,7-heptadicarboxylic acid, 5-hydroxy-1,3-benzenedicarboxylic acid,pyrazine-2,3-dicarboxylic acid, furan-2,5-dicarboxylic acid,1-nonene-6,9-dicarboxylic acid, eicosenedicarboxylic acid,4,4′-dihydroxydiphenylmethane-3,3′-dicarboxylic acid,1-amino-4-methyl-9,10-dioxo-9,10-dihydroanthracene-2,3-dicarboxylicacid, 2,5-pyridinedicarboxylic acid, cyclohexene-2,3-dicarboxylic acid,2,9-dichlorofluororubin-4,11-dicarboxylic acid,7-chloro-3-methylquinoline-6,8-dicarboxylic acid,2,4-dichlorobenzophenone-2′,5′-dicarboxylic acid,1,3-benzenedicarboxylic acid, 2,6-pyridinedicarboxylic acid,1-methylpyrrole-3,4-dicarboxylic acid,1-benzyl-1H-pyrrole-3,4-dicarboxylic acid,anthraquinone-1,5-dicarboxylic acid, 3,5-pyrazoledicarboxylic acid,2-nitrobenzene-1,4-dicarboxylic acid, heptane-1,7-dicarboxylic acid,cyclobutane-1,1-dicarboxylic acid 1,14-tetradecanedicarboxylic acid,5,6-dehydronorbornane-2,3-dicarboxylic acid, and5-ethyl-2,3-pyridinedicarboxylic acid.

In certain embodiments, the invention relates to any one of theaforementioned MOF matrices, wherein the organic ligand is atricarboxylic acid, including but not limited to2-hydroxy-1,2,3-propanetricarboxylic acid,7-chloro-2,3,8-quinolinetricarboxylic acid, 1,2,4-benzenetricarboxylicacid, 1,2,4-butanetricarboxylic acid,2-phosphono-1,2,4-butanetricarboxylic acid, 1,3,5-benzenetricarboxylicacid, 1-hydroxy-1,2,3-propanetricarboxylic acid,4,5-dihydro-4,5-dioxo-1H-pyrrolo[2,3-F]quinoline-2,7,9-tricarboxylicacid, 5-acetyl-3-amino-6-methylbenzene-1,2,4-tricarboxylic acid,3-amino-5-benzoyl-6-methylbenzene-1,2,4-tricarboxylic acid,1,2,3-propanetricarboxylic acid, and aurintricarboxylic acid.

In certain embodiments, the invention relates to any one of theaforementioned MOF matrices, wherein the organic ligand is atetracarboxylic acid, including but not limited to1,1-dioxidoperylo[1,12-BCD]thiophene-3,4,9,10-tetracarboxylic acid,perylenetetracarboxylic acids such as perylene-3,4,9,10-tetracarboxylicacid or perylene-1,12-sulfone-3,4,9,10-tetracarboxylic acid,butanetetracarboxylic acids, such as 1,2,3,4-butanetetracarboxylic acidor meso-1,2,3,4-butanetetracarboxylic acid,decane-2,4,6,8-tetracarboxylic acid,1,4,7,10,13,16-hexaoxacyclooctadecane-2,3,11,12-tetracarboxylic acid,1,2,4,5-benzenetetracarboxylic acid, 1,2,11,12-dodecanetetracarboxylicacid, 1,2,5,6-hexanetetracarboxylic acid, 1,2,7,8-octanetetracarboxylicacid, 1,4,5,8-naphthalenetetracarboxylic acid,1,2,9,10-decanetetracarboxylic acid, benzophenonetetracarboxylic acid,3,3′,4,4′-benzophenonetetracarboxylic acid,tetrahydrofurantetracarboxylic acid, andcyclopentane-1,2,3,4-tetracarboxylic acid.

In certain embodiments, the invention relates to any one of theaforementioned MOF matrices, wherein the organic ligand isacetylenedicarboxylic acid (ADC), benzenedicarboxylic acids,naphthalenedicarboxylic acids, biphenyldicarboxylic acids (for example,4,4′-biphenyldicarboxylic acid (BPDC)), bipyridinedicarboxylic acids(for example, 2,2′-bipyridinedicarboxylic acids like2,2′-bipyridine-5,5′-dicarboxylic acid), benzenetricarboxylic acids (forexample, 1,2,3-benzenetricarboxylic acid or 1,3,5-benzenetricarboxylicacid (BTC)), adamantanetetracarboxylic acid (ATC), adamantanedibenzoate(ADB), benzenetribenzoate (BTB), methanetetrabenzoate (MTB),adamantanetetrabenzoate, or dihydroxyterephthalic acids (for example,2,5-dihydroxyterephthalic acid (DHBDC)).

In certain embodiments, the invention relates to any one of theaforementioned MOF matrices, wherein the organic ligand is terephthalicacid, isophthalic acid, 2-aminoterephthalic acid,2,5-dihydroxyterephthalic acid, 1,2,3-benzenetricarboxylic acid,1,3,5-benzenetricarboxylic acid, or 2,2′-bipyridine-5,5′-dicarboxylicacid.

In certain embodiments, the invention relates to any one of theaforementioned MOF matrices, wherein the organic ligand comprises apolydentate organic ligand and a monodentate organic ligand.

In certain embodiments, organic ligands are described in U.S. Pat. No.5,648,508, hereby incorporated by reference in its entirety.

Exemplary Dopants

In certain embodiments, the invention relates to any one of theaforementioned MOF matrices, wherein the matrix further comprises adopant, thereby forming a hybrid MOF matrix, or a MOF composite matrix.In certain embodiments, the dopant is a functional material. In certainembodiments, the dopant is of a shape and size sufficient to fit intothe porous structure of MOF matrix. In certain embodiments, the dopantis acidic or basic. In certain embodiments, the dopant is apolyoxometalate (POM) or a nucleophilic amine.

In certain embodiments, the invention relates to any one of theaforementioned MOF matrices, wherein the MOF matrix comprises apolyoxometalate; and the polyoxometalate is a heteropoly acid or isopolyacid. In certain embodiments, the invention relates to any one of theaforementioned MOF matrices, wherein the MOF matrix comprises apolyoxometalate; and the polyoxometalate is phosphotungstic acid (PTA),phosphomolybdic acid, silicomolybdic acid, silicotungstic acid,phosphotungstomolybdic acid, phosphovanadomolybdic acid, or a heteropolyacid comprising tungsten or molybdenum and at least one other elementhaving a positive valence from 2 to 7. In certain embodiments, theinvention relates to any one of the aforementioned MOF matrices, whereinthe MOF matrix comprises a polyoxometalate; and the polyoxometalate isphosphotungstic acid (PTA) or PTA modified by inclusion of metal ions.In certain embodiments, the invention relates to any one of theaforementioned MOF matrices, wherein the MOF matrix comprises apolyoxometalate; and the polyoxometalate is PTA modified by inclusion ofTi, Cr, Co, or Cu.

In certain embodiments, the invention relates to any one of theaforementioned MOF matrices, wherein the MOF matrix comprises anucleophilic amine; and the nucleophilic amine is a 4-aminopyridine. Incertain embodiments, the invention relates to any one of theaforementioned MOF matrices, wherein the nucleophilic amine is4-N,N-dimethylaminopyridine (DMAP).

Exemplary Properties of Matrices of the Invention

In certain embodiments, the invention relates to any one of theaforementioned MOF matrices, wherein the MOF matrix is crystalline

In certain embodiments, the invention relates to any one of theaforementioned MOF matrices, wherein the MOF matrix is one-, two-, orthree-dimensional.

In certain embodiments, the invention relates to any one of theaforementioned MOF matrices, wherein the MOF matrix is porous. Incertain embodiments, the invention relates to any one of theaforementioned MOF matrices, wherein the MOF matrix comprises aplurality of pores. In certain embodiments, the invention relates to anyone of the aforementioned MOF matrices, wherein the MOF matrix comprisesnanopores or mesopores. In certain embodiments, nanopores are defined aspores having a diameter from about 0.1 nm to about 2 nm. In certainembodiments, mesopores are defined as pores having a diameter in therange from about 2 nm to about 50 nm. In certain embodiments, thepresence of nanoropores or mesopores can be studied using sorptionmeasurements, these measurements determining the MOF uptake capacity fornitrogen as specified in DIN 66131 and/or DIN 66134.

In certain embodiments, the invention relates to any one of theaforementioned MOF matrices, wherein the MOF matrix comprises pores thatrange in diameter from about 0.1 nm to about 30 nm. In certainembodiments, the invention relates to any one of the aforementioned MOFmatrices, wherein the MOF matrix comprises pores that range in diameterfrom about 0.1 nm to about 4 nm. In certain embodiments, the inventionrelates to any one of the aforementioned MOF matrices, wherein the MOFmatrix comprises pores that have an average diameter of about 0.1 nm toabout 30 nm. In certain embodiments, the invention relates to any one ofthe aforementioned MOF matrices, wherein the MOF matrix comprises poresthat have an average diameter of about 0.1 nm to about 4 nm. In certainembodiments, the invention relates to any one of the aforementioned MOFmatrices, wherein the MOF matrix comprises pores that have an averagediameter of about 0.1 nm, about 0.2 nm, about 0.3 nm, about 0.4 nm,about 0.5 nm, about 0.6 nm, about 0.7 nm, about 0.8 nm, about 0.9 nm,about 1.0 nm, about 1.5 nm, about 2.0 nm, about 2.5 nm, about 3.0 nm,about 3.5 nm, about 4 nm, about 4.5 nm, about 5.0 nm, about 6 nm, about7 nm, about 8 nm, about 9 nm, about 10 nm, about 12 nm, about 14 nm,about 16 nm, about 18 nm, about 20 nm, about 22 nm, about 24 nm, about26 nm, about 28 nm, or about 30 nm.

In certain embodiments, the invention relates to any one of theaforementioned MOF matrices, wherein the specific surface area of theMOF matrix, calculated according to the Langmuir model (DIN 66131,66134) for a MOF in powder form, is greater than about 5 m²/g, greaterthan about 10 m²/g, greater than about 50 m²/g, greater than about 500m²/g, greater than about 1000 m²/g, or greater than about 1500 m²/g. Incertain embodiments, the invention relates to any one of theaforementioned MOF matrices, wherein the specific surface area of theMOF matrix, calculated according to the Langmuir model (DIN 66131,66134) for a MOF in powder form, is less than about 10,000 m²/g.

In certain embodiments, the invention relates to any one of theaforementioned MOF matrices, wherein the MOF matrix catalyzesaldehyde-alcohol reactions at ambient temperature.

In certain embodiments, the invention relates to any one of theaforementioned MOF matrices, wherein the MOF matrix catalyzes the Baeyercondensation of aldehydes and phenols.

In certain embodiments, the invention relates to any one of theaforementioned MOF matrices, wherein the MOF matrix catalyzes aldehydeor ketone acetalizations.

In certain embodiments, the invention relates to any one of theaforementioned MOF matrices, wherein the MOF matrix catalyzes aldehydeself-condensation.

In certain embodiments, the invention relates to any one of theaforementioned MOF matrices, wherein the MOF matrix captures andcatalyzes reactions of acetaldehyde, acrolein, formaldehyde,butyraldehyde, crotonaldehyde, benzyl aldehyde, propionaldehyde, phenol,m-cresol, p-cresol, o-cresol, α-naphthol, or β-naphthol.

In certain embodiments, the invention relates to any one of theaforementioned MOF matrices, wherein the MOF matrix chemically orphysically adsorbs, absorbs, entraps, catalyzes, or chemically reactswith a product of tobacco combustion or pyrolysis. In certainembodiments, the invention relates to any one of the aforementioned MOFmatrices, wherein the MOF matrix adsorbs, absorbs, or converts at leastone product of tobacco combustion or pyrolysis.

In certain embodiments, the invention relates to any one of theaforementioned MOF matrices, wherein the MOF matrix catalyzescondensation reactions such as polycondensation reactions of aldehydesthat lead to (i) increasing the product molecular weight making is lessvolatile relative to the initial aldehyde, and (ii) consumption of toxicaldehyde groups. In certain embodiments, the invention relates to anyone of the aforementioned MOF matrices, wherein the MOF matrix catalyzescondensation reactions between aldehydes and phenols (Baeyer reactions),leading to the consumption of both aldehyde and phenol toxicantfamilies.

Exemplary Filter Elements of the Invention

In certain embodiments, the invention relates to a filter elementcomprising any one of the aforementioned MOF matrices.

In certain embodiments, the invention relates to any one of theaforementioned filter elements, wherein the filter element has a filterrod structure. In certain embodiments, the filter rod structure means astructure (a filter structure) formed by arranging a given number ofmono-filaments (for example, about 3,000 to about 100,000mono-filaments) in the flow direction of mainstream smoke.

In certain embodiments, the invention relates to any one of theaforementioned filter elements, wherein the filter element is capable ofreducing the quantity of contaminants in smoke.

In certain embodiments, the invention relates to any one of theaforementioned filter elements, wherein the filter element comprises afiber. In certain embodiments, the invention relates to any one of theaforementioned filter elements, wherein the fiber comprises celluloseacetate. In certain embodiments, the invention relates to any one of theaforementioned filter elements, wherein the cellulose acetate comprisesa plurality of isocyanate moieties.

In certain embodiments, the invention relates to any one of theaforementioned filter elements, wherein the filter element comprises theMOF matrix in an amount from about 0.5% to about 20% by weight. Incertain embodiments, the invention relates to any one of theaforementioned filter elements, wherein the filter element comprises theMOF matrix in about 0.5%, about 1.0%, about 1.5%, about 2.0%, about2.5%, about 3.0%, about 3.5%, about 4.0%, about 4.5%, about 5.0%, about5.5%, about 6.0%, about 6.5%, about 7.0%, about 7.5%, about 8.0%, about8.5%, about 9.0%, about 9.5%, about 10%, about 11%, about 12%, about13%, about 14%, about 15%, about 16%, about 17%, about 18%, about 19%,or about 20% by weight.

Exemplary Smoking Articles of the Invention

In certain embodiments, the invention relates to a smoking articlecomprising any one of the aforementioned filter elements. In certainembodiments, the invention relates to any one of the aforementionedsmoking articles, wherein the smoking article comprises any one of theaforementioned filter elements attached to a tobacco rod.

In certain embodiments, the invention relates to any one of theaforementioned smoking articles, wherein the smoking article is acigarette, a cigar, or a pipe.

Popular smoking articles, such as cigarettes, have a substantiallycylindrical rod-shaped structure and include a charge, roll or column ofsmokable material such as shredded tobacco (e.g., in cut filler form)surrounded by a paper wrapper thereby forming a so-called “smokable rod”or “tobacco rod.” Normally, a cigarette has a cylindrical filter elementaligned in an end-to-end relationship with the tobacco rod. Typically, afilter element comprises cellulose acetate tow plasticized usingtriacetin, and the tow is circumscribed by a paper material known as“plug wrap.” A cigarette can incorporate a filter element havingmultiple segments, and one of those segments can comprise activatedcharcoal particles. Typically, the filter element is attached to one endof the tobacco rod using a circumscribing wrapping material known as“tipping paper.” It also has become desirable to perforate the tippingmaterial and plug wrap, in order to provide dilution of drawn mainstreamsmoke with ambient air. A cigarette is employed by a smoker by lightingone end thereof and burning the tobacco rod. The smoker then receivesmainstream smoke into his or her mouth by drawing on the opposite end(e.g., the filter end) of the cigarette.

In certain embodiments, the invention relates to any one of theaforementioned smoking articles, wherein the filter element is insertedinto the smoking article.

Exemplary Methods of the Invention

In certain embodiments, the invention relates to a method of capturingcarbonylic compounds or converting carbonylic compounds into lessvolatile compounds. In certain embodiments, the capturing occurs viaphysical or chemical adsorption, absorption, or entrapping toxicantcomponents of the cigarette smoke and smoke constituents.

In certain embodiments, the invention relates to a method of adsorbingor absorbing a carbonylic compound or a phenolic compound, comprisingcontacting the carbonylic compound or phenolic compound with any one ofthe aforementioned MOF matrices.

In certain embodiments, the invention relates to a method of catalyzingthe conversion of a carbonylic compound to a non-carbonylic product,comprising contacting the carbonylic compound with any one of theaforementioned MOF matrices for an amount of time, thereby forming thenon-carbonylic product.

In certain embodiments, the invention relates to any one of theaforementioned methods, wherein the non-carbonylic product is a ketal,an acetal, a polyketal, a polyacetal, or an organic heterocycle.

In certain embodiments, the invention relates to a method of catalyzingthe conversion of a phenolic compound to a non-phenolic product or apolymeric product, comprising contacting the phenolic compound with anyone of the aforementioned MOF matrices for an amount of time, therebyforming the non-phenolic product or the polymeric product.

In certain embodiments, the invention relates to any one of theaforementioned methods, wherein the non-phenolic product is an organicheterocycle.

In certain embodiments, the invention relates to a method of catalyzingan alcohol-aldehyde condensation, comprising contacting an alcohol andan aldehyde with any one of the aforementioned MOF matrices for anamount of time. In certain embodiments, the invention relates to any oneof the aforementioned methods, wherein the alcohol is phenol. In certainembodiments, the invention relates to any one of the aforementionedmethods, wherein the alcohol is phenol from cigarette smoke. In certainembodiments, the invention relates to any one of the aforementionedmethods, wherein the alcohol is naphthol. In certain embodiments, theinvention relates to any one of the aforementioned methods, wherein thealdehyde is formaldehyde. In certain embodiments, the invention relatesto any one of the aforementioned methods, wherein the aldehyde isacetaldehyde. In certain embodiments, the invention relates to any oneof the aforementioned methods, wherein the aldehyde is benzaldehyde. Incertain embodiments, the invention relates to any one of theaforementioned methods, wherein the alcohol or the aldehyde is adsorbedonto the MOF matrix.

In certain embodiments, the invention relates to a method of acetylizingan aldehyde with an alcohol, comprising contacting the aldehyde and thealcohol with any one of the aforementioned MOF matrices.

In certain embodiments, the invention relates to any one of theaforementioned methods, wherein the aldehyde is benzaldehyde.

In certain embodiments, the invention relates to any one of theaforementioned methods, wherein the alcohol is methanol.

In certain embodiments, the invention relates to any one of theaforementioned methods, wherein the carbonylic compound or phenoliccompound is a product of tobacco combustion or pyrolysis.

In certain embodiments, the invention relates to a method ofsubstantially reducing the quantity of a toxicant in a fluid, comprisingcontacting the fluid with any one of the aforementioned MOF matrices.

In certain embodiments, the invention relates to a method ofsubstantially removing a toxicant from a fluid, comprising contactingthe fluid with any one of the aforementioned MOF matrices.

In certain embodiments, the invention relates to any one of theaforementioned methods, wherein the fluid is a gas. In certainembodiments, the invention relates to any one of the aforementionedmethods, wherein the fluid is an aerosol. In certain embodiments, theinvention relates to any one of the aforementioned methods, wherein thefluid is tobacco smoke. In certain embodiments, the invention relates toany one of the aforementioned methods, wherein the fluid is cigarettesmoke. In certain embodiments, the invention relates to any one of theaforementioned methods, wherein the fluid is mainstream cigarette smokeor sidestream cigarette smoke. Smoking articles, such as cigarettes orcigars, produce both mainstream smoke during a puff, and sidestreamsmoke during static burning.

In certain embodiments, the invention relates to any one of theaforementioned methods, wherein the toxicant is a carbonylic compound ora phenolic compound.

In certain embodiments, the invention relates to any one of theaforementioned methods, wherein the carbonylic compound comprisesacetaldehyde, acrolein, formaldehyde, butyraldehyde, crotonaldehyde,benzyl aldehyde, or propionaldehyde.

In certain embodiments, the invention relates to any one of theaforementioned methods, wherein the phenolic compound comprises phenol,m-cresol, p-cresol, o-cresol, α-naphthol, or β-naphthol.

In certain embodiments, the invention relates to any one of theaforementioned methods, wherein the quantity of toxicant in the fluid isreduced.

In certain embodiments, the invention relates to any one of theaforementioned methods, wherein the toxicant is adsorbed onto orabsorbed into the MOF matrix. In certain embodiments, the inventionrelates to any one of the aforementioned methods, wherein the toxicantis chemically converted into a less volatile substance. In certainembodiments, the less volatile substance is a ketal, an acetal, apolyketal, a polyacetal, a polymer, or an organic heterocycle.

In certain embodiments, the invention relates to a method of making anyone of the aforementioned MOF matrices. In certain embodiments, the MOFmatrices may be made in a solvent selected from the group consisting ofethanol, dimethylformamide, toluene, methanol, chlorobenzene,diethylformamide, dimethyl sulfoxide, water, hydrogen peroxide,methylamine, sodium hydroxide solution, N-methylpolidone ether,acetonitrile, benzyl chloride, triethylamine, ethylene glycol, andmixtures thereof. In certain embodiments, solvents for making any one ofthe aforementioned MOF matrices are described in U.S. Pat. No.5,648,508, hereby incorporated by reference in its entirety.

In certain embodiments, the invention relates to a method of making anyone of the aforementioned MOF matrices. In certain embodiments, theinvention relates to any one of the aforementioned methods, comprisingcontacting an aqueous PTA solution with MIL-101. In certain embodiments,the invention relates to any one of the aforementioned methods,comprising autoclaving aqueous Cr(III) nitrate and terephthalic acidsolutions. In certain embodiments, the invention relates to any one ofthe aforementioned methods, comprising autoclaving Cr(NO₃)₃,terephthalic acid, and PTA in water. In certain embodiments, theinvention relates to any one of the aforementioned methods, furthercomprising the step of evaporating the solvent.

In certain embodiments, the invention relates to any one of theaforementioned methods, wherein the pore size of the resulting MOFmatrix may be controlled. In certain embodiments, the invention relatesto any one of the aforementioned methods, the pore size of the MOFmatrix is controlled by selection of the organic ligand. While notwishing to be bound by any particular theory, in certain embodiments,the larger the organic ligand, the larger the pore diameter in theresulting MOF matrix.

In certain embodiments, the invention relates to a method of making anyone of the aforementioned filter elements. In certain embodiments, themethod comprises the step of: contacting a particle comprising any oneof the aforementioned MOF matrices with a fiber of a filter element,thereby forming a coated fiber. In certain embodiments, the inventionrelates to any one of the aforementioned methods, wherein a pendantgroup on the organic ligand reacts with a functional group on the fiber,thereby producing a reaction product. In certain embodiments, thependant group on the organic ligand is an amino group. In certainembodiments, the functional group on the fiber is an isocyanate moiety.In certain embodiments, the reaction product is a urea.

In certain embodiments, the invention relates to any one of theaforementioned methods, further comprising the step of: dissolving aplurality of particles comprising any one of the aforementioned MOFmatrices in a second solvent, thereby forming a MOF matrix solution. Incertain embodiments, the second solvent is tetrahydrofuran or acetone.In certain embodiments, the solution further comprises an additive. Incertain embodiments, the additive is toluene diisocyanate. In certainembodiments, the concentration of additive in the second solvent is fromabout 0.5% by weight to about 10% by weight. In certain embodiments, theconcentration of additive in the second solvent is about 0.5%, about1.0%, about 1.5%, about 2.0%, about 2.5%, about 3.0%, about 3.5%, about4.0%, about 4.5%, about 5.0%, about 5.5%, about 6.0%, about 6.5%, about7.0%, about 7.5%, about 8.0%, about 8.5%, about 9.0%, about 9.5%, orabout 10% by weight.

In certain embodiments, the invention relates to any one of theaforementioned methods, wherein the concentration of MOF matrix in thesecond solvent is from about 0.5% to about 20% by weight. In certainembodiments, the invention relates to any one of the aforementionedmethods, wherein the concentration of MOF matrix in the second solventis about 0.5%, about 1.0%, about 1.5%, about 2.0%, about 2.5%, about3.0%, about 3.5%, about 4.0%, about 4.5%, about 5.0%, about 5.5%, about6.0%, about 6.5%, about 7.0%, about 7.5%, about 8.0%, about 8.5%, about9.0%, about 9.5%, about 10%, about 11%, about 12%, about 13%, about 14%,about 15%, about 16%, about 17%, about 18%, about 19%, or about 20% byweight.

In certain embodiments, the invention relates to any one of theaforementioned methods, wherein the MOF matrix solution is sprayed ontothe fiber.

In certain embodiments, the invention relates to any one of theaforementioned methods, wherein the spraying is conducted in acontinuous stream of air, thereby substantially evaporating the secondsolvent substantially simultaneously.

In certain embodiments, the invention relates to any one of theaforementioned methods, further comprising the step of: maintaining thecoated fibers at a temperature for a second period of time.

In certain embodiments, the invention relates to any one of theaforementioned methods, wherein the temperature is from about 40° C. toabout 100° C. In certain embodiments, the temperature is about 40° C.,about 45° C., about 50° C., about 55° C., about 60° C., about 65° C.,about 70° C., about 75° C., about 80° C., about 85° C., about 90° C.,about 95° C., or about 100° C.

In certain embodiments, the invention relates to any one of theaforementioned methods, wherein the second period of time is from about30 min to about 90 min. In certain embodiments, the invention relates toany one of the aforementioned methods, wherein the second period of timeis about 30 min, about 40 min, about 50 min, about 60 min, about 70 min,about 80 min, or about 90 min.

EXEMPLIFICATION

The invention now being generally described, it will be more readilyunderstood by reference to the following, which is included merely forpurposes of illustration of certain aspects and embodiments of thepresent invention, and is not intended to limit the invention.

Example 1 Synthesis of Porous Catalytic Matrices

Materials

Chromium (III) nitrate nonahydrate (99%), terephthalic acid (≥99%),aluminum chloride hexahydrate (AlCl₃ 6H₂O, 99%), acetaldehyde (≥99.5%),2-amino terephthalic acid (99%), N,N-dimethylformamide (>99.9%),2-naphthol (99%), benzaldehyde (purified by redistillation, ≥99.5%),β-caryophyllene (≥98.5%, sum of enantiomers, GC), methanol (anhydrous,99.8%), phenol (≥99%) and acetamide (≥99.0%) were all obtained fromSigma-Aldrich Chemical Co. and were used as received. Hydrated12-tungstophosphoric acid (H₃PW₁₂O₄₀, PTA) (Sigma-Alrich, >99%) wasdried at 70° C. for 8 h to obtain H₃PW₁₂O₄₀.6H₂O. All other chemicalsand solvents used were obtained from commercial sources and were ofhighest purity available.

Porous MIL-101 (Cr) Matrix Synthesis

Particles of metal-organic framework (MOF) MIL-101 were synthesizedhydrothermally, utilizing either microwave (MW) or autoclave oven heatsupply. In the autoclave method, Cr(NO₃)₃.9H₂O (2.0 g, 5 mmol),terephthalic acid (0.83 g, 5 mmol) and deionized water (20 mL) wereblended and briefly sonicated resulting in a dark blue-coloredsuspension with a pH of 2.58. The suspension was placed in aTeflon®-lined autoclave bomb and kept in an oven at 218° C. for 18 hwithout stirring. After the synthesis and equilibration at roomtemperature, pH 0.5 was recorded in the suspension.

In the MW synthesis, Cr(NO₃)₃.9H₂O (1 mmol, 400 mg), terephthalic acid(166 mg, 1 mmol) and deionized water (4500 mg, 250 mmol) were blendedand briefly sonicated, resulting in a suspension with the initial pH2.60. In a separate series of experiments, the pH was adjusted as neededusing 1 M aqueous NaOH. A sample (1 mL) was withdrawn from thesuspension, placed it in a glass tube and microwaved using CEM DiscoverMW oven (CEM Corp., Matthews, N.C.) at 220° C. for 15 min using 300 mWpower under constant stirring.

After either synthesis, the MOF solids were separated from water usingcentrifuge (5,000 g, 10 min) and washed with water, methanol andacetone. The suspension in acetone was centrifuged and separated, thesolids were placed in N,N-dimethylformamide (20 mL) and the suspensionwas sonicated for 10 min and then kept at 70° C. overnight. Theresulting solids were separated by centrifugation, repeatedly washedwith methanol and acetone, dried at 75° C. overnight and then undervacuum (10⁻⁵ Torr) at ambient temperature for 2 days. Total yield of dryMIL-101 particles based on chromium was 54-63 wt %. Typical elementalanalysis, wt %: C, 48.1; Cr, 10.3.

Synthesis of MIL-101 (Cr)-phosphotungstic Acid (PTA) Hybrid Materials(MIL101/PTA)

The hybrid materials were synthesized by either autoclaving chromiumnitrate, terephthlaic acid and phosphotungstic acid mixtures in water orby impregnating already prepared MIL-101 by aqueous solution ofphosphotungstic acid in water. In a typical “joint autoclaving”synthesis (resulting MOF designated MIL101/PTA_(ja)), Cr(NO₃)₃.9H₂O (2.0g, 5 mmol), terephthalic acid (0.83 g, 5 mmol), phosphotungstic acid (2g, 0.7 mmol), and deionized water (20 mL) were blended and brieflysonicated resulting in a dark blue-colored suspension with a pH of 2.58.The suspension was placed in a Teflon®-lined autoclave bomb and kept inan oven at 218° C. for 18 h without stirring. The resultingMIL101/PTA_(aj) solids were separated by centrifugation and washed withwater, methanol, acetone and then dried under vacuum until constantweight. Elemental analysis (wt %): C, 33.1; Cr, 7.58; W, 21.8.

In the “impregnation” method, 1 g of dry MIL-101 synthesized inautoclave as described above was suspended in aqueous solution ofphosphotungstic acid (1.0 g in 20 mL). The suspension was sonicated andshaken at 300 rpm at ambient temperature for 2 days. The solids wereseparated by centrifugation and dried under vacuum. The resulting MOFwas designated MIL101/PTA_(imp). Elemental analysis (wt %): C, 33.5; Cr,9.23; W, 19.9.

Based on the elemental analysis and molecular weight of the Kegginstructure (H₃PW₁₂O₄₀, 2880 Da), we estimated the PTA content of theMIL101/PTA_(aj) and MIL101/PTA_(imp) materials to be approximately 31 wt%.

Example 2 Synthesis and Properties of NH₂-MIL-101 (al) Porous Materialand NH₂-MIL-101 (Al) Doped with Dimethlaminopyridine (DMAP)

A solution of aluminum chloride hexahydrate (0.97 g, 4.0 mmol) and2-aminoterephthalic acid (1.09 g, 6.0 mmol) in 30 mL of DMF was placedin a Teflon®-lined autoclave and kept there at 130° C. for 72 h. Theresulting yellow powder was separated by centrifugation (10,000 g, 15min), washed with acetone, separated and suspended in 200 mL methanol at75° C. for 24 h. The resulting powder was recovered from methanol bycentrifugation and dried under vacuum. MOF surface area and poreparameters were measured using a Micromeritics' ASAP® 2020 AcceleratedSurface Area and Porosimetry Analyzer (Micromeritics Corp., Norcross,Ga.). The compound's BET and Langmuir surface area values were measuredto be 2080 and 2880 m²/g, respectively, and the average pore diameterwas 2.2 nm.

For doping by DMAP, a solution of DMAP (1 g) in 30 mL methanol was addedto 1 g of NH₂-MIL-101 (Al) and the suspension was briefly sonicated andthen shaken at room temperature for 48 h. The solid particles were thenseparated by centrifugation (10,000 g, 15 min), washed by methanol anddried under vacuum at room temperature.

Example 3 Synthesis and Properties of MIL-89 Porous Material and MIL-89Doped With Dimethyaminopyridine (DMAP)

First, μ₃-oxo-triaquohexakis(acetato)triiron(III)perchlorate dihydratewas prepared as follows: Electrolytic iron metal powder (11.2 g, 0.2mol) was stirred with 100 mL of water and 51.6 mL (0.6 mol) of 70%HClO₄. The mixture was warmed to 50° C. until all of the iron hadreacted. A small amount of insoluble matter was removed bycentrifugation. After the solution was cooled to 10° C., an excess (30mL) of a 15% H₂O₂ solution was added. The solution was cooled to 5° C.,and anhydrous sodium acetate (32.8 g, 0.4 mol) was slowly added withstirring. The reaction mixture was placed in a stream of air. After 5days the majority of the solution evaporated, leaving large red-browncrystals; yield 7.99 g (30.0%). The crystals were collected, washed withtwo 25-mL portions of chilled water, and blotted with filter paper. Thecrystals were further dried for 24 h under vacuum at room temperature.

Secondly, MOF Fe(III) acetate-muconic acid 1:5 (MIL-89) was synthesizedas follows: Oxo-triaquohexakis(acetato)triiron(III) (400 mg) wasdissolved in absolute ethanol (20 mL) and some amount remainedundissolved, which was removed by centrifugation, dried and weighed. Thedissolved fraction weighed 341 mg (0.277 mmol). To that solution, 200 mg(1.4 mmol) of trans,trans-muconic acid was added. The mixture was keptin a sealed vial at 75° C. for 1 week, resulting in orange particulates.The MOF was purified by DMF, hot methanol (3 times) and dried at 75° C.for 24 h and then under vacuum (10⁻⁵ Torr) for 1 week.

MOF surface area and pore parameters were measured using aMicromeritics' ASAP® 2020 Accelerated Surface Area and PorosimetryAnalyzer (Micromeritics Corp., Norcross, Ga.). The compound's BET andLangmuir surface area values were measured to be 1880 and 2650 m²/g,respectively.

For doping by DMAP, a solution of DMAP (1 g) in 30 mL methanol was addedto 1 g of MIL-89 and the suspension was briefly sonicated and thenshaken at room temperature for 48 h. The solid particles were thenseparated by centrifugation (10,000 g, 15 min), washed by methanol anddried under vacuum at room temperature.

Example 4 Properties of Porous Matrices Based on MIL-101 (Cr)

MOF surface area and pore parameters were measured using aMicromeritics' ASAP® 2020 Accelerated Surface Area and PorosimetryAnalyzer (Micromeritics Corp., Norcross, Ga.). ThermogravimetricAnalysis (TGA) was conducted using a Q5000IR thermogravimetric analyzer(TA Instruments, Inc.). Samples were subjected to heating scans (20°C./min) in nitrogen atmosphere and in a temperature ramp mode. ¹H, ³¹Pand ¹³C NMR spectra were collected at 25±0.5° C. using a BrukerAvance-400 spectrometer operating at 400.01, 161.9 and 100 MHz,respectively. Particle size distribution in MOF suspensions in methanolwas measured using a ZetaPALS instrument (Brookhaven Instruments Corp.).The melting points were determined with a MeI-Temp II apparatus(Laboratory Devices USA) and are uncorrected. Elemental analysis wasconducted in a commercial laboratory using an ICP apparatus.

The properties of the MIL-101 (Cr) particles synthesized in deionizedwater at pH 2.6 are collected in FIG. 7, whereas the properties of theMIL101/PTA matrices are shown in FIG. 1 and FIG. 8.

Example 5 Capture and Conversion of Acrolein

Acrolein (also known as 2-propenal) is the persistent toxicant found incigarette smoke. Acrolein can cause DNA damage that is similar to thedamage seen in lung cancer patients. Since smoke contains up to 1,000times more acrolein than other DNA-damaging chemicals, it could be amajor cause of lung cancer. Acrolein also stops human cells fromrepairing DNA damage. And, like hydrogen cyanide, it kills the hairsthat normally clean our lungs of other toxins. Its reactivity is due tothe presence of its two reactive functions, vinyl and aldehyde, whichcan react individually or together. Acrolein is volatile, with boilingpoint at 53° C. and vapor pressure of 286 mbar at 20° C. In thisexample, we observed that acrolein is captured by and readilypolymerized in the presence of basic and acidic MOF to give insolublepolymers (polyacroleins).

For acrolein capture, glass vials, each containing a weighed amount ofdry powder of MIL-101, MIL101/PTA_(ja), MIL101/PTA_(imp), PTA,NH₂-MIL-101 (Al), NH₂-MIL-101 (Al) doped with DMAP, and MIL-89 andMIL-89 doped with DMAP were placed in a desiccator next to an open Petridish containing 10 g of liquid acrolein. The open vials were kept in thesealed desiccator for 5 days at room temperature, while weighing theuptake periodically by withdrawing the vials, rapidly sealing them andmeasuring weight. Equilibrium weight uptake was reached after 3 days, atwhich point no further weight increase of the vials was observed. Thesamples were prepared and measured in triplicate. The weight uptake wascalculated as WU, %=100×(Sample weight after equilibration-Initialsample weight)/Initial sample weight.

The results of the weight uptake of acrolein are given in FIG. 2. As isseen, over 420 wt % acrolein uptake was observed by MIL-101 (Cr), whichis the matrix with the highest pore volume and surface area. The uptakewas significantly reduced by doping the MIL-101 (Cr) matrix withphosphotungstic acid (PTA), despite of the fact that PTA itself causedrapid polymerization of the vapors (see uptake of PTA exceeding 530%).The formation of transparent or yellowish polymeric layers was observedin all of the samples, but was most prevalent in the case of PTA.Phosphotungstic acid is the most potent acid of the knownheteropolyacids, which causes polymerization of acrolein. It may behypothesized that rapid polymerization of acrolein around PTA embeddedinto the pores of the MIL-101 prevented further uptake of the acroleinvapors in the cases of MIL-101(Cr)/PTA matrices, which reduced theoverall acrolein uptake. Matrices MIL-101 (Al) and MIL-89 possessed muchlesser surface area than MIL-101(Cr) and thus captured lesser amounts ofacrolein. The ability of these matrices to uptake acrolein dramatically,4.5-6.5-fold, increased by their modification with DMAP, which is anefficient catalyst of acrolein polymerization. In certain embodiments,the matrices of the present invention are capable of capturing acroleinvapors up to 5-fold of the matrix weight. The captured acrolein israpidly converted into non-volatile polymeric species. Without beingbound by any theory, polymerization of acrolein by an exemplarycatalytic matrix of the present invention is shown in FIG. 3.

Example 6 Capture and Conversion of Acetaldehyde

Acetaldehyde (CH₃CHO) is a saturated aldehyde with a pungent andsuffocating odor, but at more dilute concentrations the odor is fruityand pleasant, despite being irritant and lacrymator. Acetaldehyde isextremely volatile, with a boiling point of 20.16° C. and vapor pressureat 20° C. of 0.97 atm. Acetaldehyde concentration in cigarettes is0.5-1.2 mg/cigarette and 98% of the compound is found in the vaporphase/smoke. We conducted experiments illustrating the capture ofacetaldehyde from vapor phase and its catalytic conversion into lessvolatile products as follows.

For acetaldehyde capture, borosilicate glass vials, each containing aweighed amount of dry powder of MIL-101, MIL101/PTA_(ja),MIL101/PTA_(imp), or PTA were placed in a desiccator next to an openPetri dish containing 10 g of liquid acetaldehyde, initially poured intothe dish at −20° C. Acetaldehyde rapidly evaporated from the Petri dishat room temperature, with the vapors contained inside of the sealeddesiccator. The open vials were kept in the sealed desiccator for 7 daysat room temperature, while weighing the uptake periodically bywithdrawing the vials from the desiccator, immediately sealing them andmeasuring weight. Liquid acetaldehyde was added into the Petri dishwithin the desiccator each time the desiccator was open for sampleswithdrawal, to maintain the saturated vapor atmosphere inside thedessiccator. Equilibrium weight uptake was reached after 2 days, atwhich point no further weight increase of the vials was observed. Smallsamples (0.1 mL) of liquid formed in the vials were withdrawnintermittently after 2 days. Rapid change of color from white to yellowto brown to black was observed in the liquid condensed in the vials. Thesamples were prepared and measured in triplicate. The weight uptake wascalculated as WU, %=100×(Sample weight after equilibration−Initialsample weight)/Initial sample weight.

The results of the weight uptake of acetaldehyde are given in FIG. 4. Asis seen, over 200 wt % acetaldehyde uptake was observed by porousMIL-101 (Cr) matrix. The uptake was dramatically, over 4- to 5-fold,enhanced by doping the MIL-101 (Cr) matrix with phosphotungstic acid(PTA), resulting in MIL101/PTAja and MIL101/PTAimp matrices being filledwith black liquid. The solid PTA powder completely dissolved in theblack condensate liquid formed around it, with the uptake exceeding2780%. It appeared that we unexpectedly discovered that PTA andPTA-loaded matrices are powerful condensing agents for acetaldehyde. Theliquid condensed over the (initially) solid samples of the study wasanalyzed for composition by Matrix Assisted Laser Desorption/IonizationTime of Flight (MALDI-TOF) mass spectrometry using an Applied BiosystemsModel Voyager DE-STR instrument, with α-cyano-4-hydroxycinnamic acid(ACHCA) as a matrix. A typical MALDI-TOF spectrum overlapped with theACHCA spectrum is shown in FIG. 5.

As is seen in FIG. 5, initial acetaldehyde (m/z=44, b.p.=20° C.) isalmost entirely (over 97%) converted to crotonaldehyde (m/z=70,b.p.=104° C.) (see FIG. 11), ethyl acetate (m/z=88, b.p.=77.1° C.),2-methyl-2-pentenal (m/z=98, b.p.=133-134° C.),3-hydroxy-2-methylpentanal (m/z=116, b.p.=180.5° C.), unsaturatedaldehyde products of metaldehyde (aldehyde tetramer) dehydration(m/z=158, b.p.>170° C.) and other products of higher molecular weight.Over the time of measurements, molecular weight of the products furtherincreased. Notably, the boiling points of aldol condensation productsand their dehydration show that these products are a lot less volatilethan the initial acetaldehyde. Eventually, polymerization ofacetaldehyde catalyzed by matrices was observed to produce viscouspolymeric liquids.

Example 7 Catalysis of Reactions Between Aldehyde and Naphthol

Aldehydes and phenols such as naphthol are both carcinogenic products ofthe tobacco pyrolysis occurring during smoking and are found in tar andsmoke (both vapors and particulates). In certain embodiments, thepresent invention discloses matrices that catalyze reactions betweenaldehydes and naphthols with the formation of non-volatile products. Inthe present Example, reactions between exemplary benzaldehyde andcarcinogenic 2-naphthol catalyzed by porous matrices of the presentinvention are disclosed. Without being bound by any theory, the reactionis illustrated in FIG. 6.

The reaction was conducted as follows: A finely powdered aliquot of2-naphthol (144 mg, 1.0 mmol) was mixed with 53 mg (0.5 mmol) ofbenzaldehyde and a measured amount of catalyst powder and the mixture,in a sealed stirred glass vial, was microwaved at a given temperatureranging from 60 to 90° C. for 2 to 10 min using 300 mW power underconstant stirring. A rapid dissolution of 2-naphthol in benzaldehyde wasobserved at T>60° C. At a given time, the contents of the vial wereplaced on dry ice and dissolved in 2 mL of deuterated THF or methanol,centrifuged at 15,000 g for 30 s and the supernatant solutions were kepton dry ice until ¹H NMR spectra were recorded. The separated catalystwas rinsed with methanol three times, dried under vacuum and weighed. Noside reactions such as hemiacetal or hemiketal formation with CD₃OD weredetectable under these conditions. For the reaction yield measurement,the product separated from the solid catalyst in THF was dried undervacuum, dissolved in ethanol at 75° C. and the solution was chilled to0° C. The ensued crystals of the dibenzoxanthene product were driedunder vacuum and weighed to afford the reaction yield, which wascalculated as a ratio of the actual product yield to the calculated one,based on the stoichiometry of the reaction.

Product characterization after recrystallization. ¹H NMR (400 MHz,THF-d₈) δ_(H): 5.0 (1H, —CH), 7.08 (2H, naphthalene), 7.21-7.31 (5H,benzene), 7.47 (4H, naphthalene), 7.75 (2H, naphthalene), 7.81 (2H,naphthalene), 8.17 (2H, naphthalene). ¹³C NMR (100 MHz, CDCl₃) δ_(C):45.3, 115.5, 118.8, 123.2, 126.7, 127.2, 128.4, 129.7, 133.5, 138.6,153.6. Melting temperature, 181° C. Anal. Calcd. for C₂₇H₁₈O: C, 90.47;H, 5.06; Found: C, 90.35; H, 5.07.

The results of catalysis are shown in FIG. 9.

As is seen in FIG. 9, porous matrices of MIL101 containing PTA almostcompletely and rapidly converted benzaldehyde and 2-naphthol intonon-volatile (solid, mp. 183° C.) product.

Example 8 Condensation of Acetaldehyde and Phenol

The reactions between acetaldehyde and phenol in deuterated THF (THF-d₈)were followed by ¹H NMR spectroscopy, with the reactions conducted intriplicate at 25° C. Initial concentrations of phenol and acetaldehydewere C_(pi)=0.165 or 0.33 M and C_(a0)=0.33 M, respectively. In atypical experiment, phenol (188 mg, 2 mmol) and 10 mg of powderedcatalyst were dissolved/suspended in THF-d₈ (2 mL), and 38 μL ofacetaldehyde (previously chilled at 0° C.) were injected into thereaction mixture through a syringe. By varying MIL101/PTA concentration,we conducted a series of control measurements to establish an optimumcatalyst concentration. Addition of 5 mg MIL101/PTA_(imp) orMIL101/PTA_(ja) into the initial acetaldehyde/phenol/THF-d₈ reactionmixture resulted in 1.1- to 1.6-fold lower conversion within 30 to 60min than with 10 mg of the corresponding catalyst species, whereasaddition of 20 mg did not change the reaction rate under otherwiseidentical conditions. Therefore, all further studies, except forstability studies, were conducted with 10 mg catalyst addition. Allcatalysts were kept under vacuum (10⁻⁵ Torr) prior to the reactions. Thereaction mixture was kept at 25° C. in a sealed 7-mL glass vialvigorously stirred at 800 rpm by a small magnetic bar. Whilephosphotungstic acid completely dissolved in THF, thus resulting in ahomogeneous catalytic reaction, particles of MIL-101 and MIL101/PTAformed suspensions and therefore, in these cases the catalysis washeterogeneous. Samples (350 μL) were withdrawn from the vialsintermittently, diluted 2-fold by THF-d₈ and centrifuged for 30 s at14,000×g to remove the catalyst. The catalyst was returned to the vial.¹H NMR spectra of the clear supernatant were then recorded. Thetimepoint was taken as a median of the measurement duration. In thecatalyst stability/reuse studies, the reactions were performed with 20mg catalyst. The catalyst was removed from the reaction mixture bycentrifugation (14,000 g, 30 s), the resulting tablet was dispersed in 3mL THF with brief sonication and the particles were again separated bycentrifugation. The procedure was repeated twice and the resultingparticles were separated and dried under vacuum. The recycled catalystwas weighed and analyzed for W or Cr content by elemental analysis,conducted in duplicates. The catalyst recovery (wt %) was measured as100× mass of catalyst in n-th cycle/initial mass of catalyst. Theperformance of the catalyst in each cycle was measured as describedabove.

Example 9 Reaction Between Benzaldehyde and Methanol

The reactions between benzaldehyde and methanol were conducted intriplicate at temperatures ranging from 25 to 55° C. Initialconcentrations of methanol and benzaldehyde were C_(mi)=23.5 andC_(b0)=0.474 M, respectively. In a typical experiment, dry powderedcatalyst (10 mg) was suspended in a mixture of methanol (6.7 mL, 166mmol) and benzaldehyde (340 μL, 3.34 mmol) and the reaction commenced.All catalysts were kept under vacuum (10⁻⁵ Torr) prior to the reactions.The reaction mixture was kept at 25° C. in a sealed 7-mL glass vialvigorously stirred at 800 rpm by a small magnetic bar. Whilephosphotungstic acid completely dissolved in methanol, particles ofMIL-101 and MIL101/PTA were insoluble and no organic product such asterephthalic acid was detected to leach out. Samples (200 μL) werewithdrawn from the vials intermittently and centrifuged for 30 s at14,000 g to remove the catalyst. The catalyst was returned to the vial.CDCl₃ was added to the clear supernatant and ¹H NMR spectra of theresulting solutions were then recorded. In cases when the samples couldnot be measured immediately after withdrawal from the reaction vials,they were placed into NMR tubes immediately after separation of thecatalyst and dilution by CDCl₃; the tubes were kept on dry ice prior tothe spectra measurement to quench the reaction fully. In the controlexperiment, no measurable change was observed in NMR spectra for 2 daysin samples kept under such conditions. As in the case ofacetaldehyde-phenol reaction, by varying MIL101/PTA concentration, weattempted to establish an optimum catalyst concentration. Addition of 5mg MIL101/PTA_(imp) or MIL101/PTA_(ja) into the initialbenzaldehyde/methanol reaction mixture resulted in 1.5- to 1.8-foldlower conversion within 30 to 60 min than with 10 mg of thecorresponding catalyst species, whereas addition of 20 mg did not changethe reaction rate under otherwise identical conditions. Therefore, allfurther studies were conducted with 10 mg catalyst addition, except forstability studies wherein 20 mg of the catalyst were used. Forrecycling, the catalyst removed by centrifugation from the reactionmixture was washed with THF and chilled methanol twice, dried undervacuum and weighed. Other stability parameters were measured asdescribed above for the acetaldehyde-phenol reactions.

Benzaldehyde dimethyl acetal obtained in reaction catalyzed byMIL101/PTA_(ja) followed by the product purification by flashchromatography on silica gel was observed to be a brownish pastematerial. ¹H NMR (CDCl3): d=3.37 (s, 6 H), 5.42 (s, 1 H), 7.34-7.42 (m,3H), 7.47-7.49 (m, 2 H). 13C NMR (CDCl3): d=52.3, 102.7, 126.2, 127.8,128.0, 137.6.

Example 10 Characterization of Catalysts

MOF surface area and pore parameters were measured using aMicromeritics' ASAP® 2020 Accelerated Surface Area and PorosimetryAnalyzer (Micromeritics Corp., Norcross, Ga.). ThermogravimetricAnalysis (TGA) was conducted using a Q5000IR thermogravimetric analyzer(TA Instruments, Inc.). Samples were subjected to heating scans (20°C./min) in nitrogen atmosphere and in a temperature ramp mode. ¹H and¹³C NMR spectra were collected at 25±0.5° C. using a Bruker Avance-400spectrometer operating at 400.01 and 100 MHz, respectively. Particlesize distribution in MOF suspensions in methanol was measured using aZetaPALS instrument (Brookhaven Instruments Corp.). Elemental analysiswas conducted in a commercial laboratory.

In the present study, MIL-101 framework was synthesized solvothermicallyin deionized water, without addition of toxic and corrosive hydrofluoricacid that is typically present in the MIL-101. Férey, G. et al. Science2005, 309, 2040-2042. Despite of the absence of HF, the crystalstructure of MIL-101 in the present work corresponds to the onepreviously published. Doping of the MIL-101 porous structure with PTAions results in robust particles that possess 4- to 5-fold lessersurface area than the original MOF; a significant portion of the poresis occupied by the PTA. Kegginanion of PTA possesses relatively largesize (ca. 1.3 nm diameter and 2.25 nm³ volume), so only the large cagesof MIL-101 (3.6-nm diameter, FIG. 10) can host it. Ferey, G. et al.showed that each cage can accept up to five Keggin ions, representing50% of the volume of the cage. Crystals grown as a result of jointautoclaving of the MIL-101 components and PTA resulted in particlessized 5- to 25-fold larger than those of the original MIL-101 orMIL101/PTA. Despite of the larger particle size, as shown below, thecatalytic activity of the MIL101/PTA_(ja) was virtually the same as theone of the MIL101/PTA_(imp) with its smaller particles, indicating thatthe mass transport through the MOF pores was not limiting the activity.

Example 11 Reaction Between Acetaldehyde and Phenol

Kinetics of the condensation reaction between acetaldehyde and phenol atroom temperature was studied by ¹H NMR. Acetaldehyde is readily misciblewith most organic solvents as well as phenol at ambient temperatures.However, in the presence of the catalyst, the exothermic aldehyde-phenolcondensation is extremely rapid. The rise of temperature causes furtherincrease in the reaction rate, which in turn causes a furthertemperature rise. As in the industrial processes of novolak resinproduction, we needed to utilize a non-reactive diluent as a means ofcooling. Deuterated tetrahydrofuran (THF-d₈), which also served as anNMR lock, appeared to be an efficient diluent under chosen conditions,which afforded no detectable spike of temperature upon addition ofacetaldehyde into the reaction mixture.

Typical ¹NMR spectra representing the kinetics of the acetaldehyde andphenol condensation reaction catalyzed by MIL101/PTA_(ja) in THF-d₈ at25° C. are shown in FIG. 12. As is seen in FIG. 12, in the course of thereaction, the signal of the aldehyde group proton (—HC═O) at 9.7 ppmdisappeared, while a strong signal of the methyl groups belonging to theethylidene links between phenolic rings of the condensate product(—CHCH₃) appeared at 1.34 ppm and grew. These signals were a goodreference for calculation of the aldehyde conversion (F), which wasobtained from the expression

$\begin{matrix}{F = \frac{0.33\; I_{1.3}}{I_{9.7} + {0.33\; I_{1.3}}}} & (1)\end{matrix}$where I_(1.3) and I_(9.7) are relative integrations of the correspondingmethyl and aldehyde protons, respectively, measured at time t.

The positions of the triplet centered at 7.2 ppm (two meta-positionprotons in phenol and products) and multiplet centered at 6.9 ppm (twoortho- and one para-positioned protons in phenol rings) were independentof the solvents used in the present study and did not change as thereaction proceeded. It is interesting to observe that the positions ofthe signals corresponding to the phenolic hydroxyl groups in the areas7.9-8.3 and 5 ppm were labile, depending on the extent of the reaction.Previous studies of the model phenol-aldehyde oligomers documented thatthe chemical shifts of the phenol hydroxyls are highly sensitive of theformation of intramolecular complexes, wherein phenolic and formingmethylolic hydroxyls form hydrogen bonds, resulting in changes ofchemical shifts (δ_(OH)) of up to 3 ppm. Formation and dissociation ofsuch complexes explains the observed changes in δ_(OH).

The overall reaction of the acetaldehyde-phenol condensation is shown inFIG. 13.

In the FIG. 13, we deliberately did not specify the position of themethylene bridges between the phenol rings, as both ortho- andpara-positions of the aromatic phenol ring possess the same reactivityin acid-catalyzed reactions. It is possible, however, to obtainall-ortho phenol-acetaldehyde novolac resins with uniform constitutionin other catalytic reactions such as bromomagnesium ion mediatedreaction of phenol with acetaldehyde derivatives.

From the formal definition of a reaction rate, we can define the rate ofthe condensation (FIG. 13) asr=kC_(p) ^(α)C_(a) ^(β),where C_(p) and C_(a) is the phenol and acetaldehyde concentration,respectively. Assuming that —OH group does not react, the change in thealdehyde concentration with time is as follows:

${- \frac{dCa}{dt}} = {{k_{1}C_{pp}} + {k_{2}C_{po}C_{a}}}$where C_(pp) and C_(po) is the total number of the para- and orthopositions, respectively, available for reaction.

Approximating k₁=k₂=k, we obtain

${- \frac{d\; C_{a}}{d\; t}} = {{k( {C_{p\; p} + C_{p\; o}} )}{C_{a}.}}$

The concentration of reacted aldehyde at a given time isC_(a0)-C_(a),whereC_(a0) is the initial aldehyde concentration. Thetotal concentration of the remaining ortho- and para-positions of phenolare then found from the expression C_(pp)+C_(po)=3C_(pi)-C_(ao)+C_(a).Herein, C_(pi) is the initial phenol concentration.

The rate expression can then be written as follows:

${- \frac{d\; C_{a}}{d\; t}} = {{k( {{3C_{p\; i}} - C_{a\; 0} + C_{a}} )}C_{a}}$

Denoting q=(3C _(pi) −C _(a0)), the above expression becomes

${\frac{d\; C_{a}}{( {q + C_{a}} )C_{a}} = {{- k}\; d\; t}},$which after integration results in the following relation:

${\ln\;\frac{C_{a}}{q + C_{a}}} = \;{{\ln\;\frac{C_{a}}{q + C_{a\; 0}}} - {k\; q\;{t.}}}$

Thus, expressing the initial reaction results in the coordinates

$\begin{matrix}{P = {\frac{\ln\; C_{a}}{q + C_{a0}} - {\frac{\ln\; C_{a}}{q + C_{a}}{vs}\mspace{14mu}{time}}}} & (2)\end{matrix}$we will obtain a straight line with a slope proportional to kq and,hence, arrive at an estimate of the reaction rate constant, k.

As is seen in FIG. 14, the reaction catalyzed by PTA, MIL101/PTA andMIL101 proceeded with considerable rates in the first 30 min, at whichpoint over 50% of the initial acetaldehyde were reacted. Completeconversion of acetaldehyde in the catalyzed reactions was reached withinapproximately 5 days. Spontaneous reaction without any catalyst addedresulted in only ca. 5% conversion after 5 days at room temperature. Therate constant of the initial reaction was measured by expressing thetime-dependent acetaldehyde concentration function (P) vs time (equation(2)) as shown in FIG. 15.

The slope of the linear fits (R²>0.96 in all cases) yielded theacetaldehyde-phenol condensation rate constants, k, values of which arecollected in FIG. 16, along with the catalyst turnover number (TON) andfrequency (TOF) values. The TOF was obtained from the initial slope ofthe time-dependent concentration of the converted aldehyde C^(c)_(a)/t=(C_(a0)−C_(a0)F)/t and effective catalyst concentration(C_(cat)):TOF=(C _(a0) /C _(cat))(ΔF/Δt)  (3)Similarly, the reaction half-life was calculated from the expressiont_(1/2)=ln(2)/(ΔF/Δt).

In the case of MIL-101 without PTA, we assumed that total concentrationof the Brønsted and Lewis acid sites (˜2 mmol/g), rather than theconcentration of coordinatively unsaturated cites in MIL-101 (0.7mmol/g), provides an adequate estimate of the catalytic sitesconcentration. This value was used in C_(cat) calculation.

Example 12 Acetalization of Benzaldehyde with Methanol

The reaction of acetalization of benzaldehyde (FIG. 17) using excessmethanol with the formation of benzaldehydedimethyl acetal was readilyfollowed by ¹H NMR, which enabled measurement of the reaction kinetics(FIG. 18).

As is seen in FIG. 18, in the course of the reaction, the signal of thebenzaldehyde proton (—HC═O) at 9.9 ppm disappeared, while signals at 5.3ppm of the methine group located α to both —C—O— as well as benzyl groupand 6 protons of the methyl groups of the dimethyl acetal at 3.3 ppm(—CH—O—CH₃) appeared and grew. The aldehyde conversion (F) in thisreaction was obtained from the expression

$\begin{matrix}{{F = \frac{I_{5.3}}{I_{9.9} + I_{5.3}}},} & (4)\end{matrix}$where I_(5.3) and I_(9.9) are relative integrations of the correspondingmethylene and aldehyde protons, respectively, measured at time t.

While the position of the signals of the methyl groups of methanol (3.38ppm) remained constant throughout the course of the reaction, theposition of the hydroxyl group signals varied in the range 3.7-4.3 ppm(FIG. 18). The δ_(OH) of the hydroxyl groups of methanol is known todepend strongly on the extent of the hydrogen bond formation, whichdepends of the solvent. In particular, the chemical shift of the —OHsignal in the methanol-chloroform mixtures varies with the solventcomposition in the 1.5-4.6 ppm range due to the hydrogen bonding betweenthe methanol and the solvent. Slight variations of the methanolconcentration in CDCl₃ and appearance of water, with its strongpropensity for H-bonding, in the course of the reaction, lead to thechanges of the methanolic —OH chemical shift.

The kinetics and thermodynamics of the reaction of aldehyde withalkanols over solid acid, heterogeneous catalysts, such as zeolites,clays and ion exchange resins, have been studied. A reaction mechanismfor the alkanol-aldehyde reaction involving heterogeneous catalysis wasproposed, consisting of three elementary steps: (i) hemiacetal formationfrom the adsorbed aldehyde and the alcohol; (ii) formation of water (alimiting step), and (iii) formation of the acetal. Detailed studiesinvolving the monitoring of the time-dependent activities of allreactants in the synthesis of acetaldehyde dimethylacetal on the acidresin Amberlyst-15 in a batch reactor revealed a kinetic law and rateconstants of the reaction, and accounted for the acetaldehydevolatility. However, to the best of our knowledge, no rate constantshave been reported in the case of arylaldehyde acetals, despite thereports on the formation of dimethyl acetals using trimethylorthoformate as reagent and indium-layered MOF as catalysts and frombenzaldehyde and methanol using Cu(II), Fe(II) and Al benzene di- andtricarboxylate MOFs as catalysts.

In the present work, we set out to evaluate the kinetics of the overallbenzaldehyde dimethyl acetal formation reaction catalyzed by MIL-101 andits composites with PTA and compare the performance of these materialswith those of the previously reported MOF catalysts. We avoided thedescription of the (unknown) elementary steps.

Considering the 50-fold molar excess of methanol over benzaldehyde, thechange of benzaldehyde concentration (C_(b)) with time can be describedby a pseudo-first order rate equation:

${- \frac{d\; C_{b}}{d\; t}} = {k_{obs}C_{b}}$

From the integrated form of the above equation being1n(C _(bt)/C _(b0))=1n(1−F)=−k _(obs) t,  (5)we can obtaink_(obs)using experimental ¹H NMR results such as F vs timedata, wherein F is obtained from eqn(4). The kinetics shown in FIG. 19depict rapid conversion of benzaldehyde to its dimethyl acetal in thepresence of PTA and its composites with MIL-101. The datapoints obtainedwithin the first 60 min appeared to be straight lines (R²>0.98 in allcases) in coordinates of eqn(5), enabling estimates of k_(obs), thereaction half-time t_(1/2)=1n(2)/k_(obs), and the turnover frequencyTOF=C_(b0)k_(obs)/C_(cat). These parameters are collected in FIG. 20.Importantly, a very low (<5 mol %) benzaldehyde conversion was observedwithout the catalysts, while a complete conversion was observed within48 h in the presence of all catalysts and 93-95 mol % conversion within24 h in reactions catalyzed by the MIL101/PTA composites as well as PTA.With MIL-101, the conversion reached 80 mol % after 24 h. The catalyticturnover number (TON=C_(b0)×Conversion/C_(cat)) can be calculated.Calculated per total concentration of the Bronsted and Lewis acid citesper L of the suspension, at 80% conversion after 24 h we obtain TON ofca. 140 with MIL-101 (FIG. 16). The above estimates of TON indicate thatMIL-101 is at least 10-fold more efficient a catalyst compared toCu₃(BTC)₂ MOF. Importantly, the reaction rates were 5-fold and TONvalues were 20-fold higher with the MIL101/PTA composites compared tothe unmodified MIL-101, indicating that the presence of a strongheteropolyacid in these composites enhanced the catalysis efficiencydrastically.

Example 13 Catalyst Recovery and Reuse

From the practical standpoint, maximum catalyst productivity, or kg ofproduct produced per kg of catalyst, is the measure of a catalyst'sperformance merit. Highly stable catalysts that do not becomedeactivated easily during the reaction exhibit high productivity andmany kg of product can be produced per kg of catalyst. Productivity datausing MOFs as catalysts that are necessary to determine the economics ofthe process and the possibility to develop industrial processes based onMOF catalysis are available in only a few reports. In the present work,we accessed the stability of the MIL-101 and MIL101/PTA catalysts withinfour cycles of the alcohol-aldehyde reactions. The stability parameterswere (i) overall catalyst recovery by mass, (ii) structural stability interms of PTA (Keggin ion) content in the MIL101/PTA composites or Crcontent in MIL-101, and (iii) performance in terms of kinetic rateconstants in each cycle. The results of the recovery and reuse studiesare collected in FIG. 21. As is seen, the loss of the catalyst mass over4 cycles was approximately 10 wt % for all tested catalysts. This lossis attributable to the incomplete recovery of the catalyst afterseparation by centrifugation, due to minute fraction dissolving inmethanol in the process of catalyst washing and some small catalystquantities staying on the walls of the centrifuge tubes. These lossesessentially stopped after the third cycle, and so did the losses of thePTA leaching out of the MIL-101 framework. We have previouslydemonstrated by XRD methods that prolonged and repeated exposure of theMIL-101 and its composites with PTA to organic solvents such asmethanol, THF and some others in the temperature range from ambient to90° C. did not induce any changes to the framework crystal structure.These data, along with essentially unchanged reaction rate constants(FIG. 21) demonstrate outstanding stability of the MOF catalysts. In 4cycles, 20 mg of the MIL/PTA catalyst converted approximately 750 mg ofphenol and 140 mg of acetaldehyde, or 1.35 g of benzaldehyde. Thisfinding indicates high catalyst performance merit.

Example 14 MOF Synthesis

NH₂-MIL-101 (Al). A solution of aluminum chloride hexahydrate(AlCl₃.6H₂O, 0.51 g, 2 mmol) and 2-ATA (HOOC—C₆H₃NH₂—COOH, 0.56 g, 3mmol) in DMF (99.9%, 40 mL) was kept at 130° C. for 72 h in aTeflon-lined autoclave bomb. Then the solids were separated from thesolution by centrifugation (5000 g, 10 min) and washed with DMF undersonication for 20 min. This was followed by washing with methanol atroom temperature, washing with excess hot (70° C.) methanol for 5 h, anddrying under vacuum at 80° C. until constant weight was achieved.Elemental analysis, Calcd. (for unit cell, Al₈₁₆C₆₅₂₈H₄₈₉₆N₈₁₆O₄₃₅₂):Al, 11.8; N, 6.13%; Found: Al, 12.1; N, 6.34%. The resulting MOF wasdesignated NH₂MIL101(Al)_(auto).

NH₂-MIL-53(Al). This material was synthesized by thermal treatment ofthe MOF components by either autoclaving or applying microwave. In theautoclaving method, a solution of aluminum chloride hexahydrate(AlCl₃.6H₂O, 99%, 2.55 g, 10 mmol) and 2-ATA (2.8 g, 15.5 mmol) in DMF(99.9%, 40 mL) was kept at 130° C. for 72 h in a Teflon-lined autoclavebomb. The solids were separated from the solution by centrifugation(5,000 g, 10 min) and washed with DMF under sonication for 20 min. Thiswas followed by washing with methanol at room temperature, washing withexcess hot (70° C.) methanol for 5 h, and drying under vacuum at 80° C.until constant weight was achieved. Elemental analysis, Calcd. (for unitcell, Al₄C₃₂H₂₄N₄O₂₀): Al, 12.1; N, 6.27%; Found: Al, 12.7; N, 6.75%.The resulting MOF was designated NH₂MIL53(Al)_(auto).

In the microwaving method, a solution of aluminum chloride hexahydrate(AlCl₃.6H₂O, 0.51 g, 2 mmol) and 2-ATA (0.56 g, 3 mmol) in DMF (99.9%,40 mL) was placed in a microwave oven (Discover SP-D, CEM Corp.) and waskept at 130° C. for 1 h using microwave power of 300 mW. The solids wereseparated from the solution by centrifugation (5,000 g, 10 min) andwashed with DMF under sonication for 20 min. This was followed bywashing with methanol at room temperature, washing with excess hot (70°C.) methanol for 5 h, and drying under vacuum at 80° C. until constantweight was achieved. Elemental analysis, Calcd. (for unit cell,Al₄C₃₂H₂₄N₄O₂₀): Al, 12.1; N, 6.27%; Found: Al, 12.1; N, 6.30%. Theresulting MOF was designated NH₂MIL53(Al)_(auto).

Example 15 MOF Structure

Based on XRD data and with the help of CrystalMaker® (CrystalMakerSoftware, Ltd.) and SpartanModel (Wavefunction, Inc.) software,representations of the 3-D structures of the NH₂-MIL-101(Al) andNH₂-MIL-53(Al) MOF were prepared, as shown in FIG. 22.

The functional MOF materials were characterized by high resolution TEM,nitrogen adsorption isotherms at 77 K, and TGA/DSC in a nitrogenatmosphere with temperatures up to 1200° C.

The specific BET surface areas for the NH₂-MIL-101(Al) andNH₂-MIL-53(Al) samples were 1920 and 780 m²/g, respectively.Incorporation of phosphotungstic acid (PTA) into the MOF reduced the BETsurface area 4- to 5-fold when it is introduced to the MOF pores.Thermogravimetric analysis (TGA/DSC) of NH₂-MIL-101(Al) andNH₂-MIL-53(Al) in nitrogen demonstrated release up to 6 wt % of solventat temperatures<100° C. The MOF materials decomposed only attemperatures above 450° C., thus demonstrating remarkable thermalstability.

Example 16 Amino-containing MOF Functionalized with PTA

Previous results indicated that phosphotungstic acid (PTA) appeared tobe a strong promoter of the aldol condensation of aldehydes. So, theeffects of PTA incorporation into the amino-containing MOF wasinvestigated. Two methods of PTA incorporation into the MOF wereexplored: impregnation of the already prepared MOF with aqueous solutionof PTA and heating of a mixture of the MOF components and PTA (jointheating). The latter technique was explored by two methods of the heatsupply: conventional autoclave oven and microwave.

Impregnation

In the “impregnation” method,³ 0.5 g of dry NH₂-MIL-101(Al) synthesizedin autoclave as described above was suspended in methanolic solution ofphosphotungstic acid (0.5 g in 5 mL). The suspension was sonicated andshaken at 300 rpm for 8 h. The solids were separated by centrifugation,repeatedly washed by methanol and deionized water (pH 6.2) and driedunder vacuum. The resulting MOF was designated NH₂MIL101(Al/PTA_(imp).Elemental analysis (wt %): C, 29.1; Al, 8.20; W, 23.6. Based on theelemental analysis results and molecular weight of hydrated PTA(H₃PW₁₂O₄₀.6H₂O, W content, 73.8%; MW, 2988 Da), we estimated the PTAcontent of the NH₂MIL101(Al)/PTA_(imp) materials to be approximately 107μmol/g of dry powder, or 32 wt %.

Impregnation, washing and drying procedure identical to the one abovewas performed with MOF NH₂MIL53(Al)_(auto) resulting from theautoclaving preparation method. Elemental analysis (wt %): C, 31.8; Al,8.92; W, 21.4. Based on the elemental analysis results and molecularweight of hydrated PTA (H₃PW₁₂O₄₀.6H₂O, W content, 73.8%; MW, 2988 Da),we estimated the PTA content of the NH₂MIL53(Al)/PTA_(imp) materials tobe approximately 97 tmol/g of dry powder, or 29 wt %.

The content of hydrated PTA, or P, was calculated according to theformula, P (μmol/g)=1×10⁶ (W content in the hybrid material,%)/(2988×73.8%).

Joint Heating

To obtain the MOF/PTA hybrid by a solvothermal method involvingautoclave oven, the following procedure was followed.⁴ Aluminum chloridehexahydrate (0.51 g, 2.1 mmol), 2-amino terephthalic acid (0.56 g, 3.1mmol) and phosphotungstic acid hydrate (250 mg, 0.086 mmol) weredissolved in DMF (30 mL) and the mixture was kept without stirring at130° C. in a Teflon-lined autoclave bomb for 72 h. The resultant solidswere separated by centrifugation, kept in boiling methanol at 70° C.overnight, separated, washed with acetone and dried at 80° C. overnight.The resulting MOF was designated NH₂MOF(Al)/PTA_(auto). It must be notedthat the XRD pattern of the solid structure resulting from theautoclaving of the MOF components and PTA did not resemble that ofNH₂-MIL-101(Al) or NH₂-MIL-53(Al), and hence, we used the abovedesignation.

To obtain the MOF/PTA hybrid by a solvothermal method involvingmicrowaving of a mixture of the MOF components and PTA, AlCl₃.6H₂O (507mg, 2.1 mmol), 2-aminoterephthalic acid (564 mg, 3.1 mmol) and PTAhydrate (985 mg, 0.34 mmol) were dissolved in anhydrousN,N-dimethylformamide (DMF) and the resulting solution was brought,under constant stirring, from ambient temperature to 130° C. within 5min followed by 1 h heating at 130° C. enabled by 300-mW power supply.The resulting solids were separated by centrifugation, kept in boilingmethanol at 70° C. overnight, separated and dried at 70° C. untilconstant weight. The resulting MOF was designated NH₂MIL53(Al)/PTA_(MW).

Example 17 Amino-containing MOF Functionalized by Al-i-Pro₃

NH₂MIL101 (Al)_(auto) or NH₂MIL101(Al)_(MW) MOF (0.88 g) was mixed witha solution of 0.88 g (4.3 mmol) of aluminum isopropoxide (Al-i-Pr_(0.3))in 10 mL hexane. The suspension was briefly sonicated and then dried at70° C. in an oven. The resulting dry powder was suspended with excesshexane with brief sonication, separated by centrifugation (5000 rpm) anddried.

Example 18 Performance of MOF/PTA and MOF/Al-i-Pro3 Hybrids in Captureand Chemical Conversion of Acetaldehyde Vapors

Capture and Condensation of Acetaldehyde Vapors on MOF Materials

For acetaldehyde capture, borosilicate glass vials, each containing aweighed amount of dry powder of a solid sample were placed next to anopen 5-mL wide mouth jar containing 2 g of liquid acetaldehyde,initially poured into the dish at −20° C. Both the vials and the jarwere situated in a small glass desiccator, which was sealed immediatelyafter pouring liquid acetaldehyde into the jar. Acetaldehyde rapidlyevaporated from the Petri dish at room temperature, with the vaporscontained inside of the sealed desiccator. The open vials were kept inthe desiccator for 24 h to 14 days at room temperature, while weighingthe uptake periodically by withdrawing the vials from the desiccator,immediately sealing them and measuring weight. Liquid acetaldehyde wasadded into the jar within the desiccator each time the desiccator wasopen for the samples withdrawal, to maintain the saturated vaporatmosphere inside the dessiccator. Equilibrium weight uptake was reachedafter 24 h, at which point no further weight increase of the vials wasobserved. Small samples (0.1 mL) of liquid formed in the vials werewithdrawn intermittently. Rapid change of color from white to yellow tobrown to black was observed in the liquid condensed in the vialscontaining NH₂MIL101(Al)/PTA_(imp) and NH₂MIL53(Al)/PTA_(imp) samples.The samples were prepared and weight uptake measured in triplicates. Theweight uptake was calculated as WU, %=100×(Sample weight afterequilibration−Initial sample weight)/Initial sample weight.

FIG. 23 shows acateldehyde vapor uptake by MOF samples after 24 h at 25°C. BET area of the dry MOF samples is shown as well. As is seen, nocorrelation is found between the BET area and the vapor uptake by thesamples, which indicates that the vapor uptake depended on the chemicalnature of the samples. BET area of the MOF was lowered 4-8-fold byincorporation of PTA or Al-i-Pr_(0.3) molecules into the MOF pores. Allsamples exhibited a significant uptake of the acetaldehyde from itsvapor phase, exceeding 50 wt % in all cases. The uptake byNH₂MIL101(Al)/PTA_(imp) and NH₂MIL53(Al)/PTA_(imp) was especiallypronounced, exceeding 275 wt %. The synthesis of MOF/PTA hybrids byimpregnation without heating allowed for the PTA to maintain itssuperacidic properties, thus acting as efficient catalyst of repeatedaldol condensation (FIG. 24) causing eventual formation of polymericproducts.

Rapid formation of liquid condensation products eliminated the adsorbedacetaldehyde from the MOF surface, thus driving further adsorption andincreasing the weight uptake (see FIG. 23).

Analysis of Condensation Products

The vapor condensed on the samples of the study was analyzed forcomposition by Matrix Assisted Laser Desorption/Ionization Time ofFlight (MALDI-TOF) mass spectrometry using an Applied Biosystems ModelVoyager DE-STR spectrometer, with 2,5-dihydroxybenzoic acid (DBH) as amatrix. For analysis, the acetaldehyde products adsorbed on the solidmatrix were extracted by tetrahydrofuran. The sample containing 20-30 mgof solid material was suspended in 0.5 mL THF and vortexed for 1-2 min.Then the solids were separated using a table-top centrifuge and thesupernatant was diluted 50-fold by deionized water. Thus dilutedextraction product (1 uL) was added to 1 uL of the matrix and spotted.The matrix consisted of 20 mg DHB, 500 uL acetonitrile, and 500 uL of0.1 wt % trifluoroacetic acid.

Analysis of the reaction products by MALDI-TOF (FIG. 25) confirmed thechemical conversion of acetaldehyde by the MOF/PTA_(imp) samples. Aftera few days of equilibration, no un-converted acetaldehyde was found inthe extracts.

Analysis of Reaction Between MOF and Acetaldehyde

Reaction between the MOF matrix and adsorbed and condensed acetaldehydevapor was studied as follows. MOF was dissolved in 20% NaOH/D₂O solventforming transparent solution at 5 mg/mL MOF concentration. The solutionwas diluted 50-fold with deionized water and 1 uL was added to 1 μL DHBmatrix; the mixture was spotted.

The results are shown in FIG. 26, which reveals formation of the imineproducts of reaction of acetaldehyde with the amino groups belonging to2-aminoterephthalic acid of the MOF. The mechanism of the acid-catalyzedreaction between acetaldehyde and amino groups of MOF is shown in FIG.27.

FIG. 27 also illustrates the rationale for the reduced reactivity of theMOF/PTA hybrids synthesized with the use of elevated temperature, whichleads to reduction of the acidic functionality of PTA through Lewis acid(PTA)-amine (MOF) complexation. Immobilization of phosphotungstic acidon amine-grafted mesoporous materials is well-documented. The protons inthe secondary structure of the heteropolyacids are readily exchangedwith different cations or protonizable amines, without altering theKeggin anion structure dramatically. These materials exhibit apseudoliquid phase behavior, where polar molecules like water, alcohols,amines enter into the bulk of the crystalline heteropolyacid, expandingor contracting the distance between the Keggin anions in the crystallattice, while nonpolar molecules such as hydrocarbons only adsorb onthe surface, without entering the bulk. However, on heating of themixtures of PTA and MOF components, the PTA crystal structure undergoesdramatic changes, as evidenced by XRD patterns, and the heteropolyacidloses a significant fraction of its catalytic activity of aldolcondensation of acetaldehyde.

Example 19 Immobilization of MOF Particles on Cellulose Acetate Fibers

Cellulose diacetate fibers from PMI were coated with MOF particles byspray-drying. The coating was performed by spraying fibers by a 1-10 wt% suspension of MOF in either 5 wt % solution of toluene diisocyanate(TDI) in THF or acetone. The spraying was conducted in a continuousstream of air, which rapidly dried the solvents. When TDi was appliedthe air-dried fibers/MOF materials were kept at 70° C. for 1 h, topartially cure (react) TDI with —OH groups of cellulose acetate. Uponcontacting the solvents, the fibers partially dissolved, but thedissolution was limited by rapid solvent evaporation. MOF loading intothe fibers varied, but was measured by TGA/DSC to reach up to 10 wt %.FIG. 28 shows SEM images of coated and uncoated fibers, to illustratethe outcome of the coating process.

Reactions between isocyanate and amino groups of MOF (FIG. 29) andbetween isocyanate and —OH groups of the fiber surface were uncoveredusing FTIR.

Example 20 Acetaldehyde Uptake by Unmodified and MOF-modified Fibers

Equilibrium acetaldehyde vapor uptake by CA fibers and theirMOF-modified counterparts was studied analogously to the uptake by MOF(see above). Prior to the uptake experiments, all materials weresubjected to the nitrogen adsorption measurement of their BET surfacearea. The results are shown in FIG. 30.

FIG. 30 demonstrates a positive correlation between the surface area andvapor uptake of these materials, with MOF coated on the fiber surfaceenhancing both the surface area and the vapor uptake.

INCORPORATION BY REFERENCE

The contents of the articles, patents, and patent applications, and allother documents and electronically available information mentioned orcited herein, are hereby incorporated by reference in their entirety tothe same extent as if each individual publication was specifically andindividually indicated to be incorporated by reference. Applicantsreserve the right to physically incorporate into this application anyand all materials and information from any such articles, patents,patent applications, or other physical and electronic documents.

EQUIVALENTS

The invention has been described broadly and generically herein. Thoseof ordinary skill in the art will readily envision a variety of othermeans and/or structures for performing the functions and/or obtainingthe results and/or one or more of the advantages described herein, andeach of such variations and/or modifications is deemed to be within thescope of the present invention. More generally, those skilled in the artwill readily appreciate that all parameters, dimensions, materials, andconfigurations described herein are meant to be exemplary and that theactual parameters, dimensions, materials, and/or configurations willdepend upon the specific application or applications for which theteachings of the present invention is/are used. Those skilled in the artwill recognize, or be able to ascertain using no more than routineexperimentation, many equivalents to the specific embodiments of theinvention described herein. It is, therefore, to be understood that theforegoing embodiments are presented by way of example only and that,within the scope of the appended claims and equivalents thereto, theinvention may be practiced otherwise than as specifically described andclaimed. The present invention is directed to each individual feature,system, article, material, kit, and/or method described herein. Inaddition, any combination of two or more such features, systems,articles, materials, kits, and/or methods, if such features, systems,articles, materials, kits, and/or methods are not mutually inconsistent,is included within the scope of the present invention. Further, each ofthe narrower species and subgeneric groupings falling within the genericdisclosure also form part of the invention. This includes the genericdescription of the invention with a proviso or negative limitationremoving any subject matter from the genus, regardless of whether or notthe excised material is specifically recited herein.

We claim:
 1. A smoking article, comprising a tobacco rod; and a filterelement, comprising a hybrid metal-organic framework (MOF) matrix, and afiber; wherein the hybrid MOF matrix comprises a dopant and a pluralityof metal ions or clusters coordinated to a plurality of polydentateorganic ligands selected from the group consisting of terephthalic acid,isophthalic acid, 2-aminoterephthalic acid, acetate-muconic acid, and amixture thereof; wherein the dopant is selected from the groupconsisting of a nucleophilic amine, a polyoxometalate (POM) and anucleophilic amine, phosphotungstic acid (PTA), and aluminumisopropoxide; the metal ion or cluster comprises Al, Cr, or Fe; thefilter element reduces the quantity of a toxicant; and the filterelement is attached to the tobacco rod.
 2. The smoking article of claim1, wherein the metal ion or cluster comprises Fe.
 3. The smoking articleof claim 1, wherein the polydentate organic ligand is selected from thegroup consisting of terephthalic acid, isophthalic acid,2-aminoterephthalic acid, and a mixture of acetate-muconic acid andterephthalic acid.
 4. The smoking article of claim 1, wherein thepolydentate organic ligand is selected from the group consisting ofterephthalic acid, 2-aminoterephthalic acid, and a mixture ofacetate-muconic acid and terephthalic acid.
 5. The smoking article ofclaim 1, wherein the metal ion or cluster comprises Al.
 6. The smokingarticle of claim 1, wherein the metal ion or cluster comprises Cr. 7.The smoking article of claim 1, wherein the dopant is a nucleophilicamine.
 8. The smoking article of claim 7, wherein the polydentateorganic ligand is selected from the group consisting of terephthalicacid, isophthalic acid, 2-aminoterephthalic acid, and a mixture ofacetate-muconic acid and terephthalic acid.
 9. The smoking article ofclaim 8, wherein the metal ion or cluster comprises Fe.
 10. The smokingarticle of claim 8, wherein the metal ion or cluster comprises Al. 11.The smoking article of claim 8, wherein the metal ion or clustercomprises Cr.
 12. The smoking article of claim 7, wherein thenucleophilic amine is dimethylaminopyridine (DMAP).
 13. The smokingarticle of claim 1, wherein the dopant is a polyoxometalate (POM) and anucleophilic amine.
 14. The smoking article of claim 13, wherein thepolydentate organic ligand is selected from the group consisting ofterephthalic acid, 2-aminoterephthalic acid, and a mixture ofacetate-muconic acid and terephthalic acid.
 15. The smoking article ofclaim 14, wherein the metal ion or cluster comprises Fe.
 16. The smokingarticle of claim 14, wherein the metal ion or cluster comprises Al. 17.The smoking article of claim 14, wherein the metal ion or clustercomprises Cr.
 18. The smoking article of claim 13, wherein thenucleophilic amine is dimethylaminopyridine (DMAP).
 19. The smokingarticle of claim 1, wherein the dopant is phosphotungstic acid (PTA).20. The smoking article of claim 1, wherein the dopant is aluminiumisopropoxide.